Summary of Significant Accounting Policies (Policy)	12 Months Ended
Summary of Significant Accounting Policies (Policy)	Mar. 31, 2018
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation We prepare financial statements on a 52- or 53-week year that ends on the last Saturday in March. Fiscal years 2017 and 2016 were 52-week years. Fiscal year 2018 was a 53-week year.
Principles of Consolidation	Principles of Consolidation The accompanying consolidated financial statements have been prepared in accordance with U. S. generally accepted accounting principles (U.S. GAAP) and include the accounts of the Company and its wholly-owned subsidiaries. All significant intercompany balances and transactions have been eliminated.
Reclassifications	Reclassifications Certain reclassifications have been made to prior year balances in order to conform to the current year’s presentation of financial information.
Use of Estimates	Use of Estimates The preparation of financial statements in accordance with U.S. GAAP requires the use of management estimates. These estimates are subjective in nature and involve judgments that affect the reported amounts of assets and liabilities, the disclosure of contingent assets and liabilities at fiscal year-end and the reported amounts of revenue and expenses during the reporting period. Actual results could differ from these estimates.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash and cash equivalents consist primarily of money market funds, commercial paper, and U.S. Government Treasury and Agency instruments with original maturities of three months or less at the date of purchase.
Inventories	Inventories We use the lower of cost or net realizable value to value our inventories, with cost being determined on a first-in, first-out basis. One of the factors we consistently evaluate in the application of this method is the extent to which products are accepted into the marketplace. By policy, we evaluate market acceptance based on known business factors and conditions by comparing forecasted customer unit demand for our products over a specific future period, or demand horizon, to quantities on hand at the end of each accounting period. On a quarterly and annual basis, we analyze inventories on a part-by-part basis. Product life cycles and the competitive nature of the industry are factors considered in the evaluation of customer unit demand at the end of each quarterly accounting period. Inventory on-hand in excess of forecasted demand is considered to have reduced market value and, therefore, the cost basis is adjusted to the lower of cost or net realizable value. Typically, market values for excess or obsolete inventories are considered to be zero. Inventory charges recorded for excess and obsolete inventory, including scrapped inventory, were $9.7 million and $6.7 million, in fiscal year 2018 and 2017, respectively. Inventory charges in fiscal year 2018 and 2017 related to a combination of quality issues and inventory exceeding demand.
Property, Plant and Equipment, Net	Property, Plant and Equipment, net Property, plant and equipment is recorded at cost, net of depreciation and amortization. Depreciation and amortization is calculated on a straight-line basis over estimated economic lives, ranging from three to 39 years. Leasehold improvements are depreciated over the shorter of the term of the lease or the estimated useful life. Furniture, fixtures, machinery, and equipment are all depreciated over a useful life of 3 to 10 years, while buildings are depreciated over a period of up to 39 years. In general, our capitalized software is amortized over a useful life of 3 years, with capitalized enterprise resource planning software being amortized over a useful life of 10 years. Gains or losses related to retirements or dispositions of fixed assets are recognized in the period incurred. Additionally, if impairment indicators exist, the Company will assess the carrying value of the associated asset.
Goodwill and Intangibles, Net	Goodwill and Intangibles, net Intangible assets include purchased technology licenses and patents that are reported at cost and are amortized on a straight-line basis over their useful lives, generally ranging from 1 to 10 years. Acquired intangibles include existing technology, core technology or patents, license agreements, in-process research & development, trademarks, tradenames, customer relationships, non-compete agreements, and backlog. These assets are amortized on a straight-line basis over lives ranging from one to fifteen years. Goodwill is recorded at the time of an acquisition and is calculated as the difference between the aggregate consideration paid for an acquisition and the fair value of the net tangible and intangible assets acquired. Goodwill and intangible assets deemed to have indefinite lives are not amortized but are subject to annual impairment tests. The Company tests goodwill and indefinite lived intangibles for impairment on an annual basis or more frequently if the Company believes indicators of impairment exist. Impairment evaluations involve management’s assessment of qualitative factors to determine whether it is more likely than not that goodwill and other intangible assets are impaired. If management concludes from its assessment of qualitative factors that it is more likely than not that impairment exists, then a quantitative impairment test will be performed involving management estimates of asset useful lives and future cash flows. Significant management judgment is required in the forecasts of future operating results that are used in these evaluations. If our actual results, or the plans and estimates used in future impairment analyses, are lower than the original estimates used to assess the recoverability of these assets, we could incur additional impairment charges in a future period.
Long-Lived Assets	Long-Lived Assets We test for impairment losses on long-lived assets and definite-lived intangibles used in operations when indicators of impairment are present and the undiscounted cash flows estimated to be generated by those assets are less than the assets’ carrying amounts. We measure any impairment loss by comparing the fair value of the asset to its carrying amount. We estimate fair value based on discounted future cash flows, quoted market prices, or independent appraisals.
Foreign Currency Translation	Foreign Currency Translation Some of the Company's subsidiaries utilize the local currency as the functional currency. The Company’s main entities, including the entities that generate the majority of sales and employ the majority of employees, are US dollar functional.
Define Benefit Pension Plan	Defined Benefit Pension Plan Defined benefit pension plans are accounted for based upon the provisions of ASC Topic 715, “Compensation — Retirement Benefits.” The funded status of the plan is recognized in the Consolidated Balance Sheet. Prior to the buy-in transaction discussed in Note 8, any re-measurement of plan assets and benefit obligations deemed necessary in an interim period, would be reflected in the Consolidated Balance Sheet in the subsequent interim period to reflect the overfunded or underfunded status of the plan. The Company engages external actuaries on at least an annual basis to provide a valuation of the plan’s assets and projected benefit obligation and is used to record the net periodic pension cost. On a quarterly basis, the Company evaluated current information available to determine whether the plan’s assets and projected benefit obligation should be re-measured.
Concentration of Credit Risk	Concentration of Credit Risk Financial instruments that potentially subject us to material concentrations of credit risk consist primarily of cash equivalents, marketable securities, long-term marketable securities, and trade accounts receivable. We are exposed to credit risk to the extent of the amounts recorded on the balance sheet. By policy, our cash equivalents, marketable securities, and long-term marketable securities are subject to certain nationally recognized credit standards, issuer concentrations, sovereign risk, and marketability or liquidity considerations. In evaluating our trade receivables, we perform credit evaluations of our major customers’ financial condition and monitor closely all of our receivables to limit our financial exposure by limiting the length of time and amount of credit extended. In certain situations, we may require payment in advance or utilize letters of credit to reduce credit risk. By policy, we establish a reserve for trade accounts receivable based on the type of business in which a customer is engaged, the length of time a trade account receivable is outstanding, and other knowledge that we may possess relating to the probability that a trade receivable is at risk for non-payment. We had three contract manufacturers, Pegatron, Jabil Circuits, and Hongfujin Precision who represented 24 percent, 18 percent, and 11 percent, respectively of our consolidated gross trade accounts receivable as of the end of fiscal year 2018. Hongfujin Precision, Protek and Jabil Circuits represented 20 percent, 15 percent, and 13 percent, respectively of our consolidated gross trade accounts receivable as of the end of fiscal year 2017. No other distributor or customer had receivable balances that represented more than 10 percent of consolidated gross trade accounts receivable as of the end of fiscal year 2018 and 2017. Since the components we produce are largely proprietary and generally not available from second sources, we consider our end customer to be the entity specifying the use of our component in their design. These end customers may then purchase our products directly from us, from a distributor, or through a third-party manufacturer contracted to produce their end product. For fiscal years 2018, 2017, and 2016, our ten largest end customers represented approximately 92 percent, 92 percent, and 89 percent, of our sales, respectively. For fiscal years 2018, 2017, and 2016, we had one end customer, Apple Inc., who purchased through multiple contract manufacturers and represented approximately 81 percent, 79 percent, and 66 percent, of the Company’s total sales, respectively. Samsung Electronics represented 15 percent of the Company’s total sales in fiscal year 2016. No other customer or distributor represented more than 10 percent of net sales in fiscal years 2018, 2017, or 2016.
Revenue Recognition	Revenue Recognition We recognize revenue when all of the following criteria are met: persuasive evidence that an arrangement exists, delivery of goods has occurred, the sales price is fixed or determinable and collectability is reasonably assured. Prior to the fourth quarter of fiscal year 2016, we had a number of arrangements with distributors whereby we deferred revenue at the time of shipment of our products to those distributors. As part of those arrangements, when a distributor resold those products to an end customer, the Company would credit the distributor the difference between (1) the original distributor price and the distributor’s agreed upon margin and (2) the final sales price to the end customer (known as the “Ship and Debit Arrangement”). For those transactions, revenue was deferred until the product was resold by the distributor and we determined that the final sales price to the distributor was fixed or determinable. For certain of our smaller distributors, we did not have similar Ship and Debit Arrangements and the distributors were billed at a fixed upfront price. For those transactions, revenue was recognized upon delivery to the distributor based upon the distributor’s individual shipping terms, less an allowance for estimated returns, as the Company determined that the revenue recognition criteria were met. In light of the fact that the distributor program had been declining as a portion of the overall business for several years, in fiscal year 2016 the Company performed a review of all distributor arrangements in an effort to streamline our distribution program and reduce overhead costs. Based upon this review, the Company terminated its Ship and Debit Arrangements with Distributors during the fourth quarter of fiscal year 2016. Subsequent to the termination of the Ship and Debit Arrangements, the Company began recognizing revenue for all distributors upon delivery to the distributor based upon the distributor’s individual shipping terms, less an allowance for estimated returns, as the Company’s final sales price to the distributor was fixed and determinable and the Company determined that all four criteria for revenue recognition were met. Although the Company terminated its Ship and Debit Arrangements with all distributors along with certain ancillary agreements related to the Ship and Debit Arrangements, the Company continues to grant varying levels of stock rotation and price protection rights based on individual distributor agreements. To the extent these rights are implicated in any transaction with a distributor, we continue to evaluate their effect on when the revenue recognition criteria have been met.
Warranty Expense	Warranty Expense We warrant our products and maintain a provision for warranty repair or replacement of shipped products. The accrual represents management’s estimate of probable returns. Our estimate is based on an analysis of our overall sales volume and historical claims experience. The estimate is re-evaluated periodically for accuracy.
Shipping Costs	Shipping Costs Our shipping and handling costs are included in cost of sales for all periods presented in the Consolidated Statements of Income.
Advertising Costs	Advertising Costs Advertising costs are expensed as incurred.
Stock-Based Compensation	Stock-Based Compensation Stock-based compensation is measured at the grant date based on the grant-date fair value of the awards and is recognized as an expense, on a ratable basis, over the vesting period, which is generally between 0 and 4 years. Determining the amount of stock-based compensation to be recorded requires the Company to develop estimates used in calculating the grant-date fair value of stock options and performance awards (also called market stock units). The Company calculates the grant-date fair value for stock options and market stock units using the Black-Scholes valuation model and the Monte Carlo simulation, respectively. The use of valuation models requires the Company to make estimates of assumptions such as expected volatility, expected term, risk-free interest rate, expected dividend yield, and forfeiture rates. The grant-date fair value of restricted stock units is the market value at grant date multiplied by the number of units.
Income Taxes	Income Taxes We are required to calculate income taxes in each of the jurisdictions in which we operate. This process involves calculating the actual current tax liability as well as assessing temporary differences in the recognition of income or loss for tax and accounting purposes. These differences result in deferred tax assets and liabilities, which are included in our Consolidated Balance Sheet. We record a valuation allowance when it is more likely than not that some portion or all of the deferred tax assets will not be realized. The Company evaluates the ability to realize its deferred tax assets based on all the facts and circumstances, including projections of future taxable income and expiration dates of carryover tax attributes. The calculation of our tax liabilities involves assessing uncertainties with respect to the application of complex tax rules and the potential for future adjustment of our uncertain tax positions by the Internal Revenue Service or other taxing jurisdiction. We recognize liabilities for uncertain tax positions based on the required two-step process. The first step requires us to determine if the weight of available evidence indicates that the tax position has met the threshold for recognition; therefore, we must evaluate whether it is more likely than not that the position will be sustained on audit, including resolution of any related appeals or litigation processes. The second step requires us to measure the tax benefit of the tax position taken, or expected to be taken, in an income tax return as the largest amount that is more than 50 percent likely of being realized upon ultimate settlement. We reevaluate the uncertain tax positions each quarter based on factors including, but not limited to, changes in facts or circumstances, changes in tax law, expirations of statutes of limitation, effectively settled issues under audit, and new audit activity. A change in the recognition step or measurement step would result in the recognition of a tax benefit or an additional charge to the tax provision in the period. Although we believe the measurement of our liabilities for uncertain tax positions is reasonable, we cannot assure that the final outcome of these matters will not be different than what is reflected in the historical income tax provisions and accruals. If additional taxes are assessed as a result of an audit or litigation, it could have a material effect on our income tax provision and net income in the period or periods for which that determination is made. We operate within multiple taxing jurisdictions and are subject to audit in these jurisdictions. These audits can involve complex issues which may require an extended period of time to resolve and could result in additional assessments of income tax. We believe adequate provisions for income taxes have been made for all periods.
Net Income Per Share	Net Income Per Share Basic net income per share is based on the weighted effect of common shares issued and outstanding and is calculated by dividing net income by the basic weighted average shares outstanding during the period. Diluted net income per share is calculated by dividing net income by the weighted average number of common shares used in the basic net income per share calculation, plus the equivalent number of common shares that would be issued assuming exercise or conversion of all potentially dilutive common shares outstanding. These potentially dilutive items consist primarily of outstanding stock options and restricted stock grants.
Accumulated Other Comprehensive Loss	Accumulated Other Comprehensive Loss Our accumulated other comprehensive loss is comprised of foreign currency translation adjustments, unrealized gains and losses on investments classified as available-for-sale and actuarial gains and losses on our defined benefit pension plan assets. See Note 13 — Accumulated Other Comprehensive Loss for additional discussion.
Recently Issued Accounting Pronouncements	Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2014-09, Revenue from Contracts with Customers (ASC Topic 606). The purpose of this ASU is to converge revenue recognition requirements per GAAP and International Financial Reporting Standards (IFRS). The core principle of the guidance is that an entity should recognize revenue to depict the transfer of promised goods or services to customers in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In August 2015, the FASB issued ASU 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date after public comment supported a proposal to delay the effective date of this ASU to annual reporting periods beginning after December 15, 2017, including interim reporting periods within that reporting period. The Company has completed the process of reviewing our customers’ contracts in respect of performance obligation identification and satisfaction, pricing, warranties, and return rights, among other considerations. Through this process, the Company currently expects an immaterial balance sheet impact to its first quarter fiscal year 2019 financials, upon adoption of this ASU. The standard may be adopted by full retrospective method, which applies retrospectively to each prior period presented, or by modified retrospective method with the cumulative effect adjustment recognized in beginning retained earnings as of the date of adoption. We anticipate using the modified retrospective adoption method. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842). The FASB issued this update to increase transparency and comparability by recognizing lease assets and lease liabilities on the balance sheet and disclosing key leasing arrangement details. Lessees would recognize operating leases on the balance sheet under this ASU — with the future lease payments recognized as a liability, measured at present value, and the right-of-use asset recognized for the lease term. A single lease cost would be recognized over the lease term. For terms less than twelve months, a lessee would be permitted to make an accounting policy election to recognize lease expense for such leases generally on a straight-line basis over the lease term. This ASU is effective for fiscal years beginning after December 15, 2018, including interim periods within those fiscal years. Early adoption is permitted. The modified retrospective approach is the only allowed adoption method. We currently expect that most of our operating lease commitments will be subject to the new standard and recognized as right-of-use assets and operating lease liabilities upon adoption, which will increase our total assets and total liabilities that we report relative to such amounts prior to adoption of this ASU. In June 2016, the FASB issued ASU 2016-13, Financial Instruments — Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments. This ASU requires credit losses on available-for-sale debt securities to be presented as an allowance rather than a write-down. Unlike current U.S. GAAP, the credit losses could be reversed with changes in estimates, and recognized in current year earnings. This ASU is effective for annual periods beginning after December 15, 2019, and interim periods within those annual periods. Early adoption is permitted for annual periods beginning after December 15, 2018, including interim periods. The Company is currently evaluating the impact of this ASU with no expected material impact. In October 2016, the FASB issued ASU 2016-16, Income Taxes (Topic 740): Intra-Entity Transfers of Assets Other Than Inventory. This ASU relates to income tax consequences of non-inventory intercompany asset transfers. This ASU is effective for annual periods beginning after December 15, 2017, and interim periods within those annual periods. Early adoption is permitted, as of the beginning of an annual reporting period. The guidance requires companies to apply a modified retrospective approach with a cumulative catch-up adjustment to beginning retained earnings in the period of adoption. The Company early adopted this ASU in the first quarter of fiscal year 2018 with a $0.7 million impact to beginning retained earnings. In January 2017, the FASB issued ASU 2017-01, Business Combinations (Topic 805): Clarifying the Definition of a Business. The update states that when substantially all of the fair value of the gross assets acquired (or disposed of) is concentrated in a single identifiable asset or a group of similar identifiable assets, the set is not a business, and should be treated as an asset acquisition instead. This ASU is effective for annual periods beginning after December 15, 2017, including interim periods within those annual periods. Early adoption is permitted under specific circumstances, including in an interim period, with prospective application on or after the effective date. The Company adopted this ASU and applied the related guidance to an asset acquisition in the first quarter of fiscal year 2018. In January 2017, the FASB issued ASU 2017-04, Intangibles — Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment. This ASU eliminates step two of the goodwill impairment test. An impairment charge is to be recognized for the amount by which the current value exceeds the fair value. This ASU is effective for annual periods beginning after December 15, 2019, including interim periods. Early adoption is permitted, for interim or annual goodwill impairment tests performed after January 1, 2017, and should be applied prospectively. An entity is required to disclose the nature of and reason for the change in accounting principle upon transition. That disclosure should be provided in the first annual period and in the interim period within the first annual period when the entity initially adopts the amendments in this update. The Company is currently evaluating the impact of this ASU with no expected material impact. In May 2017, the FASB issued ASU 2017-09, Compensation - Stock Compensation (Topic 718): Scope of Modification Accounting. This ASU applies to any company that changes the terms or conditions of a share-based award, considered a modification. Modification accounting would be applied unless certain conditions were met related to the fair value of the award, the vesting conditions and the classification of the modified award. This ASU is effective for annual periods beginning after December 15, 2017, with early adoption permitted. The standard should be applied prospectively to an award modified on or after the adoption date. The Company is currently evaluating the financial statement impact of this ASU with no expected material impact. In February 2018, the FASB issued ASU 2018-02, Income Statement - Reporting Comprehensive Income (Topic 220): Reclassification of Certain Tax Effects from Accumulated Other Comprehensive Income. This ASU allows for the classification of stranded tax effects resulting from the Tax Cuts and Jobs Act (the “Tax Act”) from accumulated other comprehensive income to retained earnings. This ASU is effective for annual periods beginning after December 15, 2018, with early adoption permitted. The standard should be applied in the period of adoption or retrospectively to each period (or periods) in which the effect of the change in tax rate is recognized. The Company is currently evaluating the potential financial statement impact of this ASU.