Employee Benefit Plans (Notes)	12 Months Ended
Mar. 31, 2016
Compensation and Retirement Disclosure [Abstract]
Employee Benefit Plans [Text Block]	EMPLOYEE BENEFIT PLANS The Company maintains a contributory profit-sharing plan for its domestic employees meeting certain eligibility and service requirements. The plan qualifies under Section 401(k) of the Internal Revenue Code of 1986, as amended, and allows employees to contribute up to 60% of their base salary, subject to maximum annual limitations prescribed by the IRS. The Company has a discretionary matching contribution program. All matches are provided on a quarterly basis and require the participant to be an active employee at the end of the applicable quarter. During fiscal 2016, 2015 and 2014, the Company's matching contributions to the plan totaled $4.4 million, $3.9 million and $3.6 million, respectively. The Company's 2001 Employee Stock Purchase Plan (the 2001 Purchase Plan) became effective on March 1, 2002. Under the 2001 Purchase Plan, eligible employees of the Company may purchase shares of common stock at semi-annual intervals through periodic payroll deductions. The purchase price in general will be 85% of the lower of the fair market value of the common stock on the first day of the participant's entry date into the offering period or of the fair market value on the semi-annual purchase date. Depending upon a participant's entry date into the 2001 Purchase Plan, purchase periods under the 2001 Purchase Plan consist of overlapping periods of either 24, 18, 12 or 6 months in duration. In May 2003 and August 2003, the Company's Board and stockholders, respectively, each approved an annual automatic increase in the number of shares reserved under the 2001 Purchase Plan. The automatic increase took effect on January 1, 2005, and on each January 1 thereafter during the term of the plan, and is equal to the lesser of (i) 1,500,000, (ii) one half of one percent (0.5%) of the then outstanding shares of the Company's common stock, or (iii) such lesser amount as is approved by Board of Directors. On January 1, 2016, an additional 1,017,492 shares were reserved under the 2001 Purchase Plan based on the automatic increase. Upon the approval of the Board of Directors, there were no shares added under the 2001 Purchase Plan on January 1, 2015 or 2014 based on the automatic increase provision. Since the inception of the 2001 Purchase Plan, 12,295,354 shares of common stock have been reserved for issuance and 6,651,710 shares have been issued under this purchase plan. During fiscal 1995, a purchase plan was adopted for employees in non-U.S. locations. Such plan provided for the purchase price per share to be 100% of the lower of the fair market value of the common stock at the beginning or end of the semi-annual purchase plan period. Effective May 1, 2006, the Company's Board of Directors approved a purchase price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of the semi-annual purchase plan period. On May 1, 2006, the Company's Board of Directors approved an annual automatic increase in the number of shares reserved under the plan. The automatic increase took effect on January 1, 2007, and on each January 1 thereafter during the term of the plan, and is equal to one tenth of one percent (0.1%) of the then outstanding shares of the Company's common stock. On January 1, 2016, an additional 203,498 shares were reserved under the plan based on the automatic increase. Upon the approval of the Board of Directors, there were no shares added under the plan on January 1, 2015 or 2014, based on the automatic increase provision. Since the inception of this purchase plan, 1,703,783 shares of common stock have been reserved for issuance and 1,063,360 shares have been issued under this purchase plan. Effective January 1, 1997, the Company adopted a non-qualified deferred compensation arrangement. This plan is unfunded and is maintained primarily for the purpose of providing deferred compensation for a select group of highly compensated employees as defined in ERISA Sections 201, 301 and 401. There are no Company matching contributions made under this plan. In connection with the acquisition of SMSC in August 2012, the Company assumed an unfunded Supplemental Executive Retirement Plan ("SERP"), which provides former SMSC senior management with retirement, disability and death benefits. An amendment to the SERP was executed on November 3, 2009, freezing the benefit level for existing participants as of February 28, 2010 and closing the SERP to new participants. As of March 31, 2016, the projected benefit obligation is $5.2 million. Annual benefit payments and contributions under this plan are expected to be approximately $0.7 million in fiscal 2017 and approximately $3.8 million cumulatively in fiscal 2018 through fiscal 2026. The Company has management incentive compensation plans which provide for bonus payments, based on a percentage of base salary, from an incentive pool created from operating profits of the Company, at the discretion of the Board of Directors. During fiscal 2016, 2015 and 2014, $19.1 million, $24.2 million and $24.4 million were charged against operations for these plans, respectively. The Company also has a plan that, at the discretion of the Board of Directors, provides a cash bonus to all employees of the Company based on the operating profits of the Company. During fiscal 2016, 2015 and 2014, $14.2 million, $15.9 million and $15.2 million, respectively, were charged against operations for this plan.

EMPLOYEE BENEFIT PLANS

The Company maintains a contributory profit-sharing plan for its domestic employees meeting certain eligibility and service requirements. The plan qualifies under Section 401(k) of the Internal Revenue Code of 1986, as amended, and allows employees to contribute up to 60% of their base salary, subject to maximum annual limitations prescribed by the IRS. The Company has a discretionary matching contribution program. All matches are provided on a quarterly basis and require the participant to be an active employee at the end of the applicable quarter. During fiscal 2016, 2015 and 2014, the Company's matching contributions to the plan totaled $4.4 million, $3.9 million and $3.6 million, respectively.

The Company's 2001 Employee Stock Purchase Plan (the 2001 Purchase Plan) became effective on March 1, 2002. Under the 2001 Purchase Plan, eligible employees of the Company may purchase shares of common stock at semi-annual intervals through periodic payroll deductions. The purchase price in general will be 85% of the lower of the fair market value of the common stock on the first day of the participant's entry date into the offering period or of the fair market value on the semi-annual purchase date. Depending upon a participant's entry date into the 2001 Purchase Plan, purchase periods under the 2001 Purchase Plan consist of overlapping periods of either 24, 18, 12 or 6 months in duration. In May 2003 and August 2003, the Company's Board and stockholders, respectively, each approved an annual automatic increase in the number of shares reserved under the 2001 Purchase Plan. The automatic increase took effect on January 1, 2005, and on each January 1 thereafter during the term of the plan, and is equal to the lesser of (i) 1,500,000, (ii) one half of one percent (0.5%) of the then outstanding shares of the Company's common stock, or (iii) such lesser amount as is approved by Board of Directors. On January 1, 2016, an additional 1,017,492 shares were reserved under the 2001 Purchase Plan based on the automatic increase. Upon the approval of the Board of Directors, there were no shares added under the 2001 Purchase Plan on January 1, 2015 or 2014 based on the automatic increase provision. Since the inception of the 2001 Purchase Plan, 12,295,354 shares of common stock have been reserved for issuance and 6,651,710 shares have been issued under this purchase plan.

During fiscal 1995, a purchase plan was adopted for employees in non-U.S. locations. Such plan provided for the purchase price per share to be 100% of the lower of the fair market value of the common stock at the beginning or end of the semi-annual purchase plan period. Effective May 1, 2006, the Company's Board of Directors approved a purchase price per share equal to 85% of the lower of the fair market value of the common stock at the beginning or end of the semi-annual purchase plan period. On May 1, 2006, the Company's Board of Directors approved an annual automatic increase in the number of shares reserved under the plan. The automatic increase took effect on January 1, 2007, and on each January 1 thereafter during the term of the plan, and is equal to one tenth of one percent (0.1%) of the then outstanding shares of the Company's common stock. On January 1, 2016, an additional 203,498 shares were reserved under the plan based on the automatic increase. Upon the approval of the Board of Directors, there were no shares added under the plan on January 1, 2015 or 2014, based on the automatic increase provision. Since the inception of this purchase plan, 1,703,783 shares of common stock have been reserved for issuance and 1,063,360 shares have been issued under this purchase plan.

Effective January 1, 1997, the Company adopted a non-qualified deferred compensation arrangement. This plan is unfunded and is maintained primarily for the purpose of providing deferred compensation for a select group of highly compensated employees as defined in ERISA Sections 201, 301 and 401. There are no Company matching contributions made under this plan.

In connection with the acquisition of SMSC in August 2012, the Company assumed an unfunded Supplemental Executive Retirement Plan ("SERP"), which provides former SMSC senior management with retirement, disability and death benefits. An amendment to the SERP was executed on November 3, 2009, freezing the benefit level for existing participants as of February 28, 2010 and closing the SERP to new participants. As of March 31, 2016, the projected benefit obligation is $5.2 million. Annual benefit payments and contributions under this plan are expected to be approximately $0.7 million in fiscal 2017 and approximately $3.8 million cumulatively in fiscal 2018 through fiscal 2026.

The Company has management incentive compensation plans which provide for bonus payments, based on a percentage of base salary, from an incentive pool created from operating profits of the Company, at the discretion of the Board of Directors. During fiscal 2016, 2015 and 2014, $19.1 million, $24.2 million and $24.4 million were charged against operations for these plans, respectively.

The Company also has a plan that, at the discretion of the Board of Directors, provides a cash bonus to all employees of the Company based on the operating profits of the Company. During fiscal 2016, 2015 and 2014, $14.2 million, $15.9 million and $15.2 million, respectively, were charged against operations for this plan.