Income Taxes - Provision for income taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Current:
Federal									$ 4,563	$ 6,964	$ 7,688
State									724	1,054	1,196
Total current									5,287	8,018	8,884
Deferred:
Federal									(1,688)	(254)	308
State									(268)	(38)	48
Total deferred									(1,956)	(292)	356
Income tax expense	$ (641)	$ 981	$ 1,188	$ 1,803	$ 1,702	$ 1,698	$ 2,041	$ 2,285	$ 3,331	$ 7,726	$ 9,240