Schedule of Earnings Per Share (Detail) - shares	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Weighted-Average Shares of Common Stock Outstanding	48,141,226	47,931,518	49,471,157
Assumed Exercise of Outstanding Dilutive Options	1,013,764	1,000,556	1,146,807
Less Shares Repurchased from Proceeds of Assumed Exercised Options	(727,904)	(726,223)	(768,886)
Restricted Stock Units	218,900	155,435	221,751
Weighted-Average Common Stock and Dilutive Securities Outstanding	48,645,986	48,361,286	50,070,829