Summary of Significant Accounting Policies - Schedule of Earnings Per Share Basic and Diluted (Detail) - shares	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Mar. 31, 2016
Earnings Per Share [Abstract]
Basic weighted shares	18,825,000	19,418,000	19,826,000
Treasury stock impact of stock options	217,000	152,000	178,000
Diluted weighted shares	19,042,000	19,570,000	20,004,000