Income Taxes - Components of the income tax provision (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Current taxes
Federal	$ 11,095	$ 10,982	$ 9,303
State	1,059	1,041	885
Total current taxes	12,154	12,023	10,188
Deferred taxes
Federal	1,781	(21)	143
State	170	(2)	14
Total deferred taxes	1,951	(23)	157
Total provision for income taxes	$ 14,105	$ 12,000	$ 10,345