Condensed Consolidated Statements of Comprehensive Income (Unaudited) - USD ($) $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 11,897	$ 13,589	$ 12,079	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 37,565	$ 32,278
Other comprehensive (loss) income, net of tax:
Unrealized (losses) gains on available for sale securities arising during the period	(166)				(1,193)			3,137	6,514
Change in minimum pension liability	55				74			164	222
Change in joint beneficiary agreement liability					(1)				(5)
Other comprehensive (loss) income	(111)				(1,120)			3,301	6,731
Comprehensive income	$ 11,786				$ 11,079			$ 40,866	$ 39,009