Treasury Stock - Summary of Share Repurchases and Cumulatively Since Inception of Authorization (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Equity [Abstract]
Shares repurchased	893,771	845,014	830,460
Cost	$ 31,525,000	$ 31,798,000	$ 27,179,000
Average price	$ 35.27	$ 37.63	$ 32.73
Shares repurchased, Cumulative	33,886,259	32,992,488
Cost, Cumulative	$ 391,803,000	$ 360,278,000
Average price, Cumulative	$ 11.56