Consolidated Statements of Comprehensive Income (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Mar. 31, 2010
Net earnings	$ 313,374	$ 250,264	$ 196,266
Other comprehensive income (loss), before tax:
Foreign currency translation adjustments	(2,520)	2,948	8,629
Net gain on derivative instruments (Note 10)	517	1,633	8,563
Other comprehensive income (loss), before tax	(2,003)	4,581	17,192
Net tax expense of other comprehensive income items	(191)	(443)	(2,997)
Other comprehensive income (loss), net of tax	(2,194)	4,138	14,195
Comprehensive income	$ 311,180	$ 254,402	$ 210,461