Income Taxes - Reconciliation of income tax provision computed at the U.S. federal statutory tax rates to income tax expense (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2016	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Income taxes at U.S. statutory rates	$ 11,399	$ 9,729	$ 9,940
State income taxes, net of federal tax benefit	675	589	583
Permanent differences	(23)	(29)	(35)
Other	(51)	56	(61)
Total provision for income taxes	$ 12,000	$ 10,345	$ 10,427