Credit facility (Details) (USD $)	12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2012	Jun. 27, 2013
Maturities of Long-term Debt [Abstract]
2015	$ 17,500,000
2016	17,500,000
2017	35,000,000
2018	35,000,000
2019	245,000,000
Debt Instrument, Description of Variable Rate Basis	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%
Interest Expense	48,716,000	40,915,000	34,266,000
Credit Agreement Maturity June 27, 2018 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Initiation Date	Jun. 27, 2013
Line of Credit Facility, Maximum Borrowing Capacity				2,000,000,000.0
Line of Credit Facility, Amount Outstanding	650,000,000
Maturities of Long-term Debt [Abstract]
Line of Credit Facility, Expiration Date	Jun. 27, 2018
Line of Credit Facility Increase Option				300,000,000
Debt Instrument, Unamortized Discount	1,100,000
Interest Expense	14,600,000	7,000,000	3,300,000
Short-term Debt, Weighted Average Interest Rate	1.65%
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit [Member]
Maturities of Long-term Debt [Abstract]
Period For Leverage Ratio To Determine Interest Rate Spread	preceding four fiscal quarter period
Debt Instrument Interest Rate Spread On Overdue Principal In Event Of Default				2.00%
Debt Instrument Interest Rate Spread On Overdue Amounts In Event Of Default				2.00%
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit [Member] | Debt Instrument Interest Rate Option1 [Member] | Minimum [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	0.25%
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit [Member] | Debt Instrument Interest Rate Option1 [Member] | Maximum [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit [Member] | Debt Instrument Interest Rate Option 2 [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Description of Variable Rate Basis	adjusted LIBOR rate (based on one, two, three, or six-month interest periods)
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit [Member] | Debt Instrument Interest Rate Option 2 [Member] | Minimum [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	1.25%
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit [Member] | Debt Instrument Interest Rate Option 2 [Member] | Maximum [Member]
Maturities of Long-term Debt [Abstract]
Debt Instrument, Basis Spread on Variable Rate	2.25%
Credit Agreement Maturity June 27, 2018 [Member] | Term Loan [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				350,000,000
Line of Credit Facility, Amount Outstanding	350,000,000
Credit Agreement Maturity June 27, 2018 [Member] | Revolving Credit Facility [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				1,650,000,000.00
Line of Credit Facility, Amount Outstanding	300,000,000
Credit Agreement Maturity June 27, 2018 [Member] | Foreign Line of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				125,000,000
Credit Agreement Maturity June 27, 2018 [Member] | Standby Letters of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				35,000,000
Credit Agreement Maturity June 27, 2018 [Member] | Line of Credit Facility Swingline Loan Sublimit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity				$ 25,000,000