Accumulated Other Comprehensive Income (Loss) - Changes in components of AOCI - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period			$ (3,871)
Other comprehensive income (loss), net of tax	$ (2,515)	$ 3,806	7,866	$ 2,252
Balance at the end of the period	3,995	1,875	3,995	1,875
Amortization of defined benefit pension
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(5,762)	(5,036)	(6,015)	(5,315)
Amounts reclassified from accumulated other comprehensive income (loss)	126	139	379	418
Other comprehensive income (loss), net of tax	126	139	379	418
Balance at the end of the period	(5,636)	(4,897)	(5,636)	(4,897)
Gain and Losses on sales of available for sale securities
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	12,752	3,604	2,588	5,467
Other comprehensive income (loss) before reclassifications	(2,715)	3,707	7,524	1,844
Amounts reclassified from accumulated other comprehensive income (loss)			(75)
Other comprehensive income (loss), net of tax	(2,715)	3,707	7,449	1,844
Balance at the end of the period	10,037	7,311	10,037	7,311
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(480)	(499)	(444)	(529)
Other comprehensive income (loss) before reclassifications	32	(95)	(91)	(152)
Amounts reclassified from accumulated other comprehensive income (loss)	42	55	129	142
Other comprehensive income (loss), net of tax	74	(40)	38	(10)
Balance at the end of the period	(406)	(539)	(406)	(539)
Accumulated Other Comprehensive Income (Loss).
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	6,510	(1,931)	(3,871)	(377)
Other comprehensive income (loss) before reclassifications	(2,683)	3,612	7,433	1,692
Amounts reclassified from accumulated other comprehensive income (loss)	168	194	433	560
Other comprehensive income (loss), net of tax	(2,515)	3,806	7,866	2,252
Balance at the end of the period	$ 3,995	$ 1,875	$ 3,995	$ 1,875