Income Taxes - Summary of Income Tax Provision (Detail) - USD ($)	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Current - Federal	$ 16,600,000	$ 16,534,000	$ 21,978,000
Current - State	2,591,000	136,000	2,656,000
Subtotal	19,191,000	16,670,000	24,634,000
Deferred - Federal	(1,679,000)	312,000	(2,367,000)
Deferred - State	23,000	(8,000)	(152,000)
Subtotal	(1,656,000)	304,000	(2,519,000)
Total	$ 17,535,000	$ 16,974,000	$ 22,115,000