CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Statement of Comprehensive Income [Abstract]
Net Income	$ 319,564	$ 444,081	$ 600,801
Other comprehensive income (loss):
Foreign currency translation adjustments, net of zero tax	(1,324)	17,846	(18,932)
Unrealized gain (loss) on derivative instruments and other, net of zero tax	9,096	26,744	(35,417)
Comprehensive income	$ 327,336	$ 488,671	$ 546,452