Earnings Per Share - Components of Denominator for Basic Earnings Per Common Share and Diluted Earnings Per Common Share (Detail) - shares		3 Months Ended		6 Months Ended
		Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic earnings per Common Share:
Weighted-average common shares outstanding for basic earnings per share calculation		9,876,000	9,766,000	9,859,000	9,741,000
Diluted earnings per Common Share:
Weighted-average basic shares outstanding		9,876,000	9,766,000	9,859,000	9,741,000
Stock options	[1]	301,000	196,000	235,000	196,000
Weighted-average common shares outstanding for diluted earnings per share calculation		10,177,000	9,962,000	10,094,000	9,937,000

[1] During the three and six month periods ended September 30, 2015, options to purchase 50,000 and 128,750 shares of common stock, respectively, and during the three and six month periods ended September 30, 2014, options to purchase 207,500 shares of common stock were excluded from the computation of diluted earnings per share because the exercise prices of these options were greater than the average market price of the common share and the effect of their conversion would be antidilutive.