Change in Number of Shares of Common Stock Outstanding (Detail) - shares	12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2018
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Shares outstanding, beginning balance	42,620,750	41,915,000	43,447,536
Purchase of treasury stock	(581,140)	(726,347)	(1,756,831)
Shares issued in acquisition (in shares)		1,177,630
Shares issued as part of equity-based compensation plans, net of equity awards surrendered for option price and taxes	283,695	254,467	224,295
Shares outstanding, ending balance	42,323,305	42,620,750	41,915,000