Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended							9 Months Ended
	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Sep. 30, 2016	Sep. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 12,199	$ 9,405	$ 10,674	$ 11,422	$ 12,694	$ 11,366	$ 8,336	$ 32,278	$ 32,396
Other comprehensive income (loss), net of tax:
Unrealized (losses) gains on available for sale securities arising during the period	(1,193)				2,316			6,514	(429)
Change in minimum pension liability	74				112			222	334
Change in joint beneficiary agreement liability	(1)							(5)
Other comprehensive (loss) income	(1,120)				2,428			6,731	(95)
Comprehensive income	$ 11,079				$ 15,122			$ 39,009	$ 32,301