Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Current
Federal									$ 17,004	$ 16,474	$ 12,092
State									995	540	452
Total									17,999	17,014	12,544
Deferred
Federal									12,625	8,649	(169)
State									1,126	642	(116)
Total									13,751	9,291	(285)
Total income tax expense	$ 10,149	$ 7,742	$ 6,842	$ 7,017	$ 7,361	$ 7,108	$ 5,941	$ 5,895	$ 31,750	$ 26,305	$ 12,259