Discontinued Operations and Disposal Groups [Abstract] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Table] Disposal Group Name [Axis] Disposal Group Name [Axis] Disposal Groups, Including Discontinued Operations, Name [Domain] Disposal Groups, Including Discontinued Operations, Name [Domain] Theatre Rigging Manufacturing [Member] Theatre Rigging Manufacturing [Member] Theatre Rigging Manufacturing [Member] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items] Gain from sale of division Discontinued Operation, Gain (Loss) on Disposal of Discontinued Operation, Net of Tax Assets sold Disposal Group, Including Discontinued Operation, Assets Accounts payable sold Disposal Group, Including Discontinued Operation, Accounts Payable Statement of Financial Position [Abstract] LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Equity [Abstract] SHAREHOLDERS' EQUITY: Stockholders' Equity Attributable to Parent [Abstract] Common stock, no par value (in dollars per share) Common Stock, No Par Value Common stock, authorized (in shares) Common Stock, Shares Authorized Common stock, issued (in shares) Common Stock, Shares, Issued Treasury stock, at cost (in shares) Treasury Stock, Shares Goodwill and Intangible Assets Disclosure [Abstract] Goodwill Goodwill Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Event [Table] Subsequent Event [Table] Subsequent Event Type [Axis] Subsequent Event Type [Axis] Subsequent Event Type [Domain] Subsequent Event Type [Domain] Subsequent Event [Member] Subsequent Event [Member] Subsequent Event [Line Items] Subsequent Event [Line Items] Cash dividend declared per share (in dollars per share) Common Stock, Dividends, Per Share, Declared Derivative Instruments and Hedging Activities Disclosure [Abstract] Schedule of Notional Amounts of Outstanding Derivative Positions Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Income Tax Disclosure [Abstract] Unrecognized tax benefits that would affect our effective tax rate if recognized Unrecognized Tax Benefits that Would Impact Effective Tax Rate Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount Effective Income Tax Rate Reconciliation, Tax Credit, Research, Amount Receivables [Abstract] Receivables Financing Receivables [Text Block] Fair Value Disclosures [Abstract] Fair Value Measurement Fair Value Disclosures [Text Block] Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Stock Options Employee Stock Option [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive securities excluded from computation of earnings per share (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive securities excluded from computation of earnings per share, weighted average exercise price (dollars per share) Antidilutive Securities Excluded from Computation of Earnings Per Share, Weighted Average Exercise Price Antidilutive Securities Excluded from Computation of Earnings Per Share, Weighted Average Exercise Price Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Repurchase of equipment guarantees Repurchase of Leased Equipment Guarantee [Member] Repurchase of Leased Equipment Guarantee [Member] Performance guarantees Performance Guarantee [Member] Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Letter of credit and bank guarantees agreements Financial Standby Letter of Credit [Member] Surety bonds Surety Bond [Member] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum Minimum [Member] Maximum Maximum [Member] Guarantor Obligations Guarantor Obligations [Line Items] Guarantees: Guarantees [Abstract] Guarantees total obligations Guarantor Obligations, Maximum Exposure, Undiscounted Performance guarantees outstanding Loss Contingency Accrual Warranties: Product Warranties Disclosures [Abstract] Standard parts warranty period Product Warranty Accrual, Standard Parts Warranty Coverage Term Product Warranty Accrual, Standard Parts Warranty Coverage Term Installation warranty period Product Warranty Accrual, Installation Warranty Coverage Term Product Warranty Accrual, Installation Warranty Coverage Term Movement in Standard Product Warranty Accrual Movement in Standard Product Warranty Accrual [Roll Forward] Beginning accrued warranty costs Product Warranty Accrual Warranties issued during the period Product Warranty Accrual, Warranties Issued Settlements made during the period Product Warranty Accrual, Payments Changes in accrued warranty costs for pre-existing warranties during the period, including expirations Product Warranty Accrual, Preexisting, Increase (Decrease) Ending accrued warranty costs Conditional purchase commitment Conditional Purchase Commitment, Amount Conditional Purchase Commitment, Amount Purchase Obligation, Fiscal Year Maturity Purchase Obligation, Fiscal Year Maturity [Abstract] 2015 Purchase Obligation, Due in Next Twelve Months 2016 Purchase Obligation, Due in Second Year 2017 Purchase Obligation, Due in Third Year 2018 Purchase Obligation, Due in Fourth Year 2019 Purchase Obligation, Due in Fifth Year Total Purchase Obligation Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Segment Reporting [Abstract] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Segments [Axis] Segments [Axis] Segments [Domain] Segments [Domain] Commerical Commerical [Member] Commerical [Member] Live Events Live Events [Member] Live Events [Member] High School Park and Recreation [Member] High School Park and Recreation [Member] High School Park and Recreation [Member] Transportation Transportation [Member] Transportation [Member] International International [Member] International [Member] Unallocated Segment Reconciling Items [Member] Segment Reporting Information Segment Reporting Information [Line Items] Number of business units Number of Reportable Segments Net sales Revenue, Net Contribution margin Contribution Margin Contribution Margin Depreciation and amortization Depreciation, Depletion and Amortization [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization Non-allocated operating expenses: Operating Expenses [Abstract] General and administrative General and Administrative Expense Product design and development Research and Development Expense Operating (loss) income Operating Income (Loss) Nonoperating income (expense): Nonoperating Income (Expense) [Abstract] Interest income Investment Income, Net Interest expense Interest Expense Other income (expense), net Other Nonoperating Income (Expense) (Loss) income before income taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax (benefit) expense Income Tax Expense (Benefit) Net income Net Income (Loss) Attributable to Parent Marketable Securities [Abstract] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Statement of Comprehensive Income [Abstract] Net income Other comprehensive loss: Other Comprehensive Income (Loss), Net of Tax [Abstract] Cumulative translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Unrealized gain (loss) on available-for-sale securities, net of tax Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Total other comprehensive loss, net of tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Comprehensive (loss) income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Derivative [Table] Derivative [Table] Derivative, by Nature [Axis] Derivative, by Nature [Axis] Derivative, Name [Domain] Derivative, Name [Domain] U.S. Dollars/Australian Dollars USD to AUD [Member] USD to AUD [Member] USD to JPY [Member] USD to JPY [Member] USD to JPY [Member] U.S. Dollars/Canadian Dollars USD to CAD [Member] USD to CAD [Member] U.S. Dollars/British Pounds USD to GBP [Member] [Member] USD to GBP [Member] [Member] USD to SGD USD to SGD [Member] USD to SGD [Member] USD to NZD USD to NZD [Member] USD to NZD [Member] U.S. Dollars/Euros USD to EUR [Member] USD to EUR [Member] Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Recurring Basis Fair Value, Measurements, Recurring [Member] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Level 2 Fair Value, Inputs, Level 2 [Member] Derivative Derivative [Line Items] Derivatives-currency forward contract, asset Foreign Currency Contract, Asset, Fair Value Disclosure Foreign Currency Exchange Forward Contracts: Derivative, Notional Amount Derivatives - currency forward contracts, liability Foreign Currency Contracts, Liability, Fair Value Disclosure Business Combinations [Abstract] Business Combination Business Combination Disclosure [Text Block] Schedule of Operating Leased Assets [Table] Schedule of Operating Leased Assets [Table] Leases, Purchase Price Option [Axis] Leases, Purchase Price Option [Axis] Leases, Purchase Price Option [Axis] Leases, Purchase Price Option [Domain] Leases, Purchase Price Option [Domain] Leases, Purchase Price Option [Domain] January 1, 2015 to December 31, 2016 January 1, 2015 to December 31, 2016 [Member] January 1, 2015 to December 31, 2016 [Member] Year ending December 2017 January 1, 2017 to December 31, 2017 [Member] January 1, 2017 to December 31, 2017 [Member] Year ending December 2018 January 1, 2018 to December 31, 2018 [Member] January 1, 2018 to December 31, 2018 [Member] Operating Leased Assets Operating Leased Assets [Line Items] Operating leases, purchase option price Operating Leases, Purchase Option Price Operating Leases, Purchase Option Price Operating leases, rent expense Operating Leases, Rent Expense, Net Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2015 Operating Leases, Future Minimum Payments, Remainder of Fiscal Year 2016 Operating Leases, Future Minimum Payments, Due in Two Years 2017 Operating Leases, Future Minimum Payments, Due in Three Years 2018 Operating Leases, Future Minimum Payments, Due in Four Years 2019 Operating Leases, Future Minimum Payments, Due in Five Years Total Operating Leases, Future Minimum Payments Due Organization, Consolidation and Presentation of Financial Statements [Abstract] Recently Issued Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Schedule of Earnings Per Share Reconciliation Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Income Statement [Abstract] Cost of goods sold Cost of Revenue Gross profit Gross Profit Operating expenses: Selling expense Selling Expense Total operating expenses Operating Expenses Other income (expense), net Weighted average shares outstanding: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings per share: Basic (in dollars per share) Earnings Per Share, Basic Diluted (in dollars per share) Earnings Per Share, Diluted Income Taxes Income Tax Disclosure [Text Block] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Schedule of Accounts, Notes, Loans and Financing Receivable [Table] Receivable Type [Axis] Receivable Type [Axis] Receivable Type [Domain] Receivable [Domain] Financing Receivable Financing Receivable [Member] Receivables Accounts, Notes, Loans and Financing Receivable [Line Items] Allowance for doubtful accounts Allowance for Doubtful Accounts Receivable, Current Long-term contracts and lease receivables, present value Financing Receivable, Net Contract and lease receivables annual interest rates Loans and Leases Receivable, Interest Rate Loans and Leases Receivable, Interest Rate Long-term contracts and lease receivables, face amount Financing Receivable, Gross Retainage on construction-type contracts, expected to be collected in one year Contract Receivable Retainage, Next Twelve Months Schedule of Product Warranty Liability Schedule of Product Warranty Liability [Table Text Block] Schedule of Future Minimum Rental Payments for Operating Leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Long-term Purchase Commitment Long-term Purchase Commitment [Table Text Block] Segment Disclosure Segment Reporting Disclosure [Text Block] Subsequent Events Subsequent Events [Text Block] Schedule of Goodwill Schedule of Goodwill [Table Text Block] Available-for-sale Securities Available-for-sale Securities [Table Text Block] Investments Classified by Contractual Maturity Date Investments Classified by Contractual Maturity Date [Table Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Current Reporting Status Entity Filer Category Entity Common Stock, Shares Outstanding Document Fiscal Year Focus Document Fiscal Period Focus Document Type Amendment Flag Document Period End Date Basis of Presentation and Summary of Critical Accounting Policies Significant Accounting Policies [Text Block] Inventory Disclosure [Abstract] Raw materials Inventory, Raw Materials, Net of Reserves Work-in-process Inventory, Work in Process, Net of Reserves Finished goods Inventory, Finished Goods, Net of Reserves Inventories Inventory, Net Statement of Cash Flows [Abstract] CASH FLOWS FROM OPERATING ACTIVITIES: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation Depreciation Amortization Amortization Amortization of premium/discount on marketable securities Accretion (Amortization) of Discounts and Premiums, Investments Gain on sale of property, equipment and other assets Gain (Loss) on Disposition of Property Plant Equipment Share-based compensation Share-based Compensation Excess tax benefits from share-based compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Provision for doubtful accounts Provision for Doubtful Accounts Deferred income taxes, net Deferred Income Tax Expense (Benefit) Change in operating assets and liabilities Increase (Decrease) in Other Operating Assets and Liabilities, Net Net cash provided by operating activities Net Cash Provided by (Used in) Operating Activities CASH FLOWS FROM INVESTING ACTIVITIES: Net Cash Provided by (Used in) Investing Activities [Abstract] Purchases of property and equipment Payments to Acquire Property, Plant, and Equipment Proceeds from sale of property, equipment and other assets Proceeds from Sale of Property, Plant, and Equipment Purchases of marketable securities Payments to Acquire Marketable Securities Proceeds from sales or maturities of marketable securities Proceeds from Sale and Maturity of Marketable Securities Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Net cash used in investing activities Net Cash Provided by (Used in) Investing Activities CASH FLOWS FROM FINANCING ACTIVITIES: Net Cash Provided by (Used in) Financing Activities [Abstract] Payments on notes payable Repayments of Notes Payable Proceeds from exercise of stock options Proceeds from Stock Options Exercised Excess tax benefits from share-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Principal payments on long-term obligations Repayments of Long-term Debt Dividends paid Payments of Ordinary Dividends, Common Stock Net cash used in financing activities Net Cash Provided by (Used in) Financing Activities EFFECT OF EXCHANGE RATE CHANGES ON CASH Effect of Exchange Rate on Cash and Cash Equivalents NET (DECREASE) INCREASE IN CASH AND CASH EQUIVALENTS Cash and Cash Equivalents, Period Increase (Decrease) CASH AND CASH EQUIVALENTS: Cash and Cash Equivalents [Abstract] Beginning of period Cash and Cash Equivalents, at Carrying Value End of period Cash payments for: Cash payments for: [Abstract] Interest Interest Paid Income taxes, net of refunds Income Taxes Paid, Net Supplemental schedule of non-cash investing and financing activities: Noncash Investing and Financing Items [Abstract] Demonstration equipment transferred to inventory Demonstration equipment transferred to inventory Value of demonstration equipment transferred to inventory in noncash transaction during the reporting period. Purchase of property and equipment included in accounts payable Capital Expenditures Incurred but Not yet Paid Contributions of common stock under the employee stock purchase plan Stock Issued Inventories Inventory Disclosure [Text Block] ASSETS Assets [Abstract] CURRENT ASSETS: Assets, Current [Abstract] Cash and cash equivalents Restricted cash Restricted Cash and Cash Equivalents, Current Marketable securities Available-for-sale Securities, Current Accounts receivable, net Accounts Receivable, Net, Current Inventories, net Costs and estimated earnings in excess of billings Costs in Excess of Billings, Current Current maturities of long-term receivables Notes, Loans and Financing Receivable, Net, Current Prepaid expenses and other assets Prepaid Expense and Other Assets, Current Deferred income taxes Deferred Tax Assets, Net of Valuation Allowance, Current Income tax receivables Income Taxes Receivable, Current Total current assets Assets, Current Long-term receivables, less current maturities Notes, Loans and Financing Receivable, Net, Noncurrent Goodwill Goodwill Intangibles, net Finite-Lived Intangible Assets, Net Investment in affiliates and other assets Advertising Rights, Net and Other Cost of equipment is recorded as advertising rights where advertising agreements have not sold for the full value of the equipment at normal margins, reported on the balance sheet as noncurrent assets, and other assets not otherwise specified in the taxonomy. Deferred income taxes Deferred Tax Assets, Net of Valuation Allowance, Noncurrent Total noncurrent assets Noncurrent Assets Excluding Property Plant and Equipment Sum of the carrying amounts as of the balance sheet date of all assets excluding property, plant, and equipment that are expected to be realized in cash, sold or consumed after one year or beyond the normal operating cycle, if longer. PROPERTY AND EQUIPMENT: Property, Plant and Equipment, Net [Abstract] Land Land Buildings Buildings and Improvements, Gross Machinery and equipment Machinery and Equipment, Gross Office furniture and equipment Furniture and Fixtures, Gross Computer software and hardware Capitalized Computer Software And Equipment Gross Gross amount, at the balance sheet date, capitalized computer software and equipment costs. Equipment held for rental Equipment held for rental Gross amount, as of the balance sheet date, of long-lived, depreciable equipment held for rental. Demonstration equipment Demonstration equipment Gross amount, as of the balance sheet date, of long-lived, depreciable equipment used for demonstration. Transportation equipment Transportation equipment Gross amount, as of the balance sheet date, of long-lived, depreciable equipment used for transportation. Property and equipment, gross Property, Plant and Equipment, Gross Less accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Property and equipment, net Property, Plant and Equipment, Net TOTAL ASSETS Assets CURRENT LIABILITIES: Liabilities, Current [Abstract] Notes payable, bank Short-term Bank Loans and Notes Payable Accounts payable Accounts Payable, Current Accrued expenses Accrued Liabilities, Current Warranty obligations Product Warranty Accrual, Current Billings in excess of costs and estimated earnings Billings in Excess of Cost, Current Customer deposits (billed or collected) Customer Deposits, Current Deferred revenue (billed or collected) Deferred Revenue, Current Current portion of other long-term obligations Other Long-term Debt, Current Income taxes payable Accrued Income Taxes, Current Deferred income taxes Deferred Tax Liabilities, Net, Current Total current liabilities Liabilities, Current Long-term warranty obligations Product Warranty Accrual, Noncurrent Long-term deferred revenue (billed or collected) Deferred Revenue, Noncurrent Other long-term obligations, less current maturities Other Liabilities, Noncurrent Deferred income taxes Deferred Tax Liabilities, Net, Noncurrent Total long-term liabilities Liabilities, Noncurrent TOTAL LIABILITIES Liabilities Common Stock, no par value, authorized 120,000,000 shares; 43,632,681 and 43,166,731 shares issued at January 31, 2015 and April 26, 2014, respectively Common Stock, Value, Issued Additional paid-in capital Additional Paid in Capital Retained earnings Retained Earnings (Accumulated Deficit) Treasury Stock, at cost, 19,680 shares Treasury Stock, Value Accumulated other comprehensive (loss) income Accumulated Other Comprehensive Income (Loss), Net of Tax TOTAL SHAREHOLDERS' EQUITY Stockholders' Equity Attributable to Parent TOTAL LIABILITIES AND SHAREHOLDERS' EQUITY Liabilities and Equity Schedule of Fair Value Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Geographical [Axis] Geographical [Axis] Geographical [Domain] Geographical [Domain] United States UNITED STATES Outside U.S. Outside United States [Member] Outside United States [Member] Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Net sales: Geographic Areas, Revenues from External Customers [Abstract] Sales Revenues Long-lived assets: Geographic Areas, Long-Lived Assets [Abstract] Long-lived assets Long-Lived Assets Earnings Per Share EPS Earnings Per Share [Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Level 1 Fair Value, Inputs, Level 1 [Member] Total Estimate of Fair Value Measurement [Member] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Debt and Equity Securities [Domain] Major Types of Debt and Equity Securities [Domain] Certificates of deposit Certificates of Deposit [Member] U.S. Government securities US Government Agencies Debt Securities [Member] U.S. Government sponsored entities US Government-sponsored Enterprises Debt Securities [Member] Municipal obligations US States and Political Subdivisions Debt Securities [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Cash and cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Restricted cash Restricted Cash and Cash Equivalents, Fair Value Disclosure Restricted Cash and Cash Equivalents, Fair Value Disclosure Available-for-sale securities: Available-for-sale Securities Assets, net Assets (Liabilities), Net, Fair Value Disclosure Assets (Liabilities), Net, Fair Value Disclosure Derivative Financial Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Schedule of Segment Reporting Information, by Segment Schedule of Segment Reporting Information, by Segment [Table Text Block] Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas Schedule of Revenue from External Customers and Long-Lived Assets, by Geographical Areas [Table Text Block] Net income Net Income (Loss) Attributable to Parent [Abstract] Basic earnings per share Dilution associated with stock compensation plans Dilutive Securities, Effect on Basic Earnings Per Share, Options and Restrictive Stock Units Diluted earnings per share Net Income (Loss) Available to Common Stockholders, Diluted Shares Weighted Average Number of Shares Outstanding Reconciliation [Abstract] Basic earnings per share (in shares) Dilution associated with stock compensation plans (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted earnings per share (in shares) Per share income Earnings Per Share Reconciliation [Abstract] Basic earnings per share (in dollars per share) Dilution associated with stock compensation plans (in dollars per share) Incremental Common Shares Attributable to Share-based Payment Arrangements, Per Share Amount Incremental Common Shares Attributable to Share-based Payment Arrangements, Per Share Amount Diluted earnings per share (in dollars per share) Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities [Table] Schedule of Available-for-sale Securities Schedule of Available-for-sale Securities [Line Items] Less than 12 months Available-for-sale Securities, Debt Maturities, Next Twelve Months, Fair Value Greater than 12 months Available-for-sale Securities, Debt Maturities, Year Two Through Five, Fair Value Total Available-for-sale Securities, Debt Securities Schedule of Goodwill [Table] Schedule of Goodwill [Table] Goodwill Goodwill [Line Items] Goodwill Goodwill [Roll Forward] Balance as of April 26, 2014 Disposal of automated rigging systems for theatre applications Goodwill, Written off Related to Sale of Business Unit Acquisition, net of cash required Goodwill, Acquired During Period Foreign currency translation Goodwill, Translation Adjustments Balance as of January 31, 2015 Amortized Cost Available-for-sale Debt Securities, Amortized Cost Basis Unrealized Gains Available-for-sale Securities, Accumulated Gross Unrealized Gain, before Tax Unrealized Losses Available-for-sale Securities, Accumulated Gross Unrealized Loss, before Tax Fair Value Schedule of Inventories Schedule of Inventory, Current [Table Text Block] Schedule of Business Acquisitions, by Acquisition [Table] Schedule of Business Acquisitions, by Acquisition [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Unpatented Technology Unpatented Technology [Member] Customer Relationships Customer Relationships [Member] Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Data Display Data Display [Member] Data Display [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Percentage of voting interests acquired Business Acquisition, Percentage of Voting Interests Acquired Goodwill acquired during period Acquired finite-lived intangible asset Finite-lived Intangible Assets Acquired Weighted average useful life Acquired Finite-lived Intangible Assets, Weighted Average Useful Life