Derivative Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Mar. 31, 2012
Forward currency exchange contracts outstanding
Notional amount of foreign currency derivatives	$ 141,186	$ 146,661
Singapore Dollar [Member]
Forward currency exchange contracts outstanding
Notional amount of foreign currency derivatives	60,229	60,925
Euro [Member]
Forward currency exchange contracts outstanding
Notional amount of foreign currency derivatives	37,866	41,467
Indian Rupee [Member]
Forward currency exchange contracts outstanding
Notional amount of foreign currency derivatives	18,718	18,943
British Pound [Member]
Forward currency exchange contracts outstanding
Notional amount of foreign currency derivatives	13,031	14,250
Japanese Yen [Member]
Forward currency exchange contracts outstanding
Notional amount of foreign currency derivatives	$ 11,342	$ 11,076