Stockholders' Equity - Stock Repurchase Plan (Details) - USD ($) $ / shares in Units, shares in Thousands		12 Months Ended			15 Months Ended
	Feb. 28, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2016	Jan. 31, 2015	Jun. 30, 2012
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Maximum stock repurchase amount approved by Board of Directors							$ 200,000,000
Number of shares repurchased (in shares)	3,823,000
Average stock price of shares repurchased (in dollars per share)	$ 52.31
2015 Stock Repurchase Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Remaining stock repurchase amount approved by Board of Directors		$ 65,294,000				$ 200,000,000
Treasury stock acquired (in shares)				377
Treasury stock acquired cost method				$ 27,900,000
Treasury stock acquired average cost per share (in usd per share)				$ 74.09	$ 66.69
Treasury stock number of shares held (in shares)		2,020,000
Treasury stock value		$ 134,706,000
2012 and 2015 Repurchase Program
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Treasury stock acquired (in shares)		222,000	1,420,000	1,436,000
Treasury stock acquired cost method		$ 12,572,000	$ 94,200,000	$ 107,200,000
Treasury stock acquired average cost per share (in usd per share)		$ 56.51	$ 66.32	$ 74.68