Condensed Consolidated Statements of Comprehensive Income - USD ($) $ in Thousands	3 Months Ended						6 Months Ended
	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Jun. 30, 2016	Jun. 30, 2015
Statement of Comprehensive Income [Abstract]
Net income	$ 9,405	$ 10,674	$ 11,422	$ 12,694	$ 11,366	$ 8,336	$ 20,079	$ 19,702
Other comprehensive income, net of tax:
Unrealized gains (losses) on available for sale securities arising during the period	4,157				(2,754)		7,707	(2,745)
Change in minimum pension liability	148				111		148	222
Change in joint beneficiary agreement liability	(4)						(4)
Other comprehensive income (loss)	4,301				(2,643)		7,851	(2,523)
Comprehensive income	$ 13,706				$ 8,723		$ 27,930	$ 17,179