Derivative Financial Instruments (Details) (Foreign currency exchange contracts, USD $) In Thousands, unless otherwise specified	9 Months Ended
	Dec. 31, 2012 program	Mar. 31, 2012
Derivative Financial Instruments
Number of hedging programs maintained	3
U.S. dollar notional equivalent market value	$ 75,342	$ 95,950
Maximum outstanding term of derivative instruments	21 months
Derivatives designated as hedging instruments
Derivative Financial Instruments
Period hedged by Cash Flow Program	24 months
Additional period after which the contract is deemed "ineffective"	2 months
Unrealized net losses related to derivative instruments expected to be reclassified from AOCI into earnings during the next 12 months	4,307
Other current assets	131	101
Other long-term assets	60	330
Accrued expenses and other current liabilities	4,438	5,418
Long-term liabilities	$ 1,332	$ 1,819
Derivatives not Designated as Hedging Instrument
Derivative Financial Instruments
Maturity period of Balance Sheet Program derivatives	30 days
Maximum maturity period of UK Revenue and Cost Program derivatives	90 days