Credit facility (Notes)	6 Months Ended
Sep. 30, 2012
Credit Facility [Abstract]
Debt Disclosure [Text Block]	Credit Facility On August 12, 2011, the Company entered into a credit agreement among the Company, the lenders from time to time that are parties thereto and JPMorgan Chase Bank, N.A., as administrative agent (the "Credit Agreement"). The Credit Agreement provides for a $750 million revolving credit facility, with a $100 million foreign currency sublimit, a $25 million letter of credit sublimit and a $15 million swingline loan sublimit, terminating on August 12, 2016 (the "Maturity Date"). The Credit Agreement also contains an increase option permitting the Company, subject to certain requirements, to arrange with existing lenders and/or new lenders for them to provide up to an aggregate of $250 million in additional commitments, which may be for revolving loans or term loans. Proceeds of loans made under the Credit Agreement may be used for working capital and general corporate purposes. No loans were made nor letters of credit issued under the Credit Agreement at closing. At September 30, 2012, $600.0 million of borrowings were outstanding under the credit agreement. The funds were used to finance a portion of the SMSC acquisition on August 2, 2012. The loans bear interest, at the Company's option, at the base rate plus a spread of 0.50% to 1.50% or an adjusted LIBOR rate (based on one, two, three, or six-month interest periods) plus a spread of 1.50% to 2.50%, in each case with such spread being determined based on the consolidated leverage ratio for the preceding four fiscal quarter period. The base rate means the highest of JPMorgan Chase Bank, N.A.'s prime rate, the federal funds rate plus a margin equal to 0.50% and the adjusted LIBOR rate for a 1-month interest period plus a margin equal to 1.00%. Swingline loans accrue interest at a per annum rate based on the base rate plus the applicable margin for base rate loans. Base rate loans may only be made in U.S. dollars. The Company is also obligated to pay other customary administration fees and letter of credit fees for a credit facility of this size and type. Interest is due and payable in arrears quarterly for loans bearing interest at the base rate and at the end of an interest period (or at each three month interval in the case of loans with interest periods greater than three months) in the case of loans bearing interest at the adjusted LIBOR rate. Interest expense on loans related to the credit agreement was approximately $2.3 million in the three months ended September 30, 2012. There was no interest expense related to loans on the credit agreement for the three months ended June 30, 2012 or the three and six months ended September 30, 2011. Principal, together with all accrued and unpaid interest, is due and payable on the maturity date. The Company may prepay the loans and terminate the commitments, in whole or in part, at any time without premium or penalty, subject to certain conditions including minimum amounts in the case of commitment reductions and reimbursement of certain costs in the case of prepayments of LIBOR loans. The Company's obligations under the Credit Agreement are guaranteed by certain of its subsidiaries meeting materiality thresholds set forth in the Credit Agreement. To secure the Company's obligations under the Credit Agreement, the Company and its domestic subsidiaries will be required to pledge the equity securities of certain of their respective material subsidiaries, subject to certain exceptions and limitations. The Credit Agreement contains customary affirmative and negative covenants, including covenants that limit or restrict the Company and its subsidiaries' ability to, among other things, incur subsidiary indebtedness, grant liens, merge or consolidate, dispose of assets, make investments, make acquisitions, enter into certain transactions with affiliates, pay dividends or make distributions, repurchase stock, enter into restrictive agreements and enter into sale and leaseback transactions, in each case subject to customary exceptions for a credit facility of this size and type. The Company is also required to maintain compliance with a consolidated leverage ratio and a consolidated interest coverage ratio. At September 30, 2012, the Company was in compliance with these covenants. The Credit Agreement includes customary events of default that, include among other things, non-payment defaults, inaccuracy of representations and warranties, covenant defaults, cross default to material indebtedness, bankruptcy and insolvency defaults, material judgment defaults, ERISA defaults and a change of control default. The occurrence of an event of default could result in the acceleration of the obligations under the Credit Agreement. Under certain circumstances, a default interest rate will apply on all obligations during the existence of an event of default under the Credit Agreement at a per annum rate equal to 2.00% above the applicable interest rate for any overdue principal and 2.00% above the rate applicable for base rate loans for any other overdue amounts.

Credit Facility

On August 12, 2011, the Company entered into a credit agreement among the Company, the lenders from time to time that are parties thereto and JPMorgan Chase Bank, N.A., as administrative agent (the "Credit Agreement"). The Credit Agreement provides for a $750 million revolving credit facility, with a $100 million foreign currency sublimit, a $25 million letter of credit sublimit and a $15 million swingline loan sublimit, terminating on August 12, 2016 (the "Maturity Date"). The Credit Agreement also contains an increase option permitting the Company, subject to certain requirements, to arrange with existing lenders and/or new lenders for them to provide up to an aggregate of $250 million in additional commitments, which may be for revolving loans or term loans. Proceeds of loans made under the Credit Agreement may be used for working capital and general corporate purposes. No loans were made nor letters of credit issued under the Credit Agreement at closing. At September 30, 2012, $600.0 million of borrowings were outstanding under the credit agreement. The funds were used to finance a portion of the SMSC acquisition on August 2, 2012.

The loans bear interest, at the Company's option, at the base rate plus a spread of 0.50% to 1.50% or an adjusted LIBOR rate (based on one, two, three, or six-month interest periods) plus a spread of 1.50% to 2.50%, in each case with such spread being determined based on the consolidated leverage ratio for the preceding four fiscal quarter period. The base rate means the highest of JPMorgan Chase Bank, N.A.'s prime rate, the federal funds rate plus a margin equal to 0.50% and the adjusted LIBOR rate for a 1-month interest period plus a margin equal to 1.00%. Swingline loans accrue interest at a per annum rate based on the base rate plus the applicable margin for base rate loans. Base rate loans may only be made in U.S. dollars. The Company is also obligated to pay other customary administration fees and letter of credit fees for a credit facility of this size and type.

Interest is due and payable in arrears quarterly for loans bearing interest at the base rate and at the end of an interest period (or at each three month interval in the case of loans with interest periods greater than three months) in the case of loans bearing interest at the adjusted LIBOR rate. Interest expense on loans related to the credit agreement was approximately $2.3 million in the three months ended September 30, 2012. There was no interest expense related to loans on the credit agreement for the three months ended June 30, 2012 or the three and six months ended September 30, 2011. Principal, together with all accrued and unpaid interest, is due and payable on the maturity date. The Company may prepay the loans and terminate the commitments, in whole or in part, at any time without premium or penalty, subject to certain conditions including minimum amounts in the case of commitment reductions and reimbursement of certain costs in the case of prepayments of LIBOR loans.

The Company's obligations under the Credit Agreement are guaranteed by certain of its subsidiaries meeting materiality thresholds set forth in the Credit Agreement. To secure the Company's obligations under the Credit Agreement, the Company and its domestic subsidiaries will be required to pledge the equity securities of certain of their respective material subsidiaries, subject to certain exceptions and limitations.

The Credit Agreement contains customary affirmative and negative covenants, including covenants that limit or restrict the Company and its subsidiaries' ability to, among other things, incur subsidiary indebtedness, grant liens, merge or consolidate, dispose of assets, make investments, make acquisitions, enter into certain transactions with affiliates, pay dividends or make distributions, repurchase stock, enter into restrictive agreements and enter into sale and leaseback transactions, in each case subject to customary exceptions for a credit facility of this size and type. The Company is also required to maintain compliance with a consolidated leverage ratio and a consolidated interest coverage ratio. At September 30, 2012, the Company was in compliance with these covenants.

The Credit Agreement includes customary events of default that, include among other things, non-payment defaults, inaccuracy of representations and warranties, covenant defaults, cross default to material indebtedness, bankruptcy and insolvency defaults, material judgment defaults, ERISA defaults and a change of control default. The occurrence of an event of default could result in the acceleration of the obligations under the Credit Agreement. Under certain circumstances, a default interest rate will apply on all obligations during the existence of an event of default under the Credit Agreement at a per annum rate equal to 2.00% above the applicable interest rate for any overdue principal and 2.00% above the rate applicable for base rate loans for any other overdue amounts.