Earnings Per Share - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jul. 17, 2015	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Repayments of Convertible Debt				$ 172,388
Shares issued from treasury stock to settle conversion premium on Convertible Notes	1,889,431		1,889,431	1,889,431
Accelerated Share Repurchase Agreement [Member]
Earnings Per Share, Basic, by Common Class, Including Two Class Method [Line Items]
Stock Repurchased and Retired During Period, Shares		1,495,714		2,961,444
Accelerated Share Repurchases, Final Price Paid Per Share		$ 66.86		$ 56.19