Accumulated Other Comprehensive Income (Loss) - Changes in components of AOCI - (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period			$ (3,871)
Other comprehensive income (loss), net of tax	$ 3,005	$ (4,929)	10,381	$ (1,554)
Balance at the end of the period	6,510	(1,931)	6,510	(1,931)
Amortization of defined benefit pension
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(5,889)	(5,175)	(6,015)	(5,315)
Amounts reclassified from accumulated other comprehensive income (loss)	126	139	252	279
Other comprehensive income (loss), net of tax	126	139	252	279
Balance at the end of the period	(5,763)	(5,036)	(5,763)	(5,036)
Gain and Losses on sales of available for sale securities
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	9,887	8,730	2,588	5,467
Other comprehensive income (loss) before reclassifications	2,865	(5,126)	10,240	(1,863)
Amounts reclassified from accumulated other comprehensive income (loss)			(76)
Other comprehensive income (loss), net of tax	2,865	(5,126)	10,164	(1,863)
Balance at the end of the period	12,752	3,604	12,752	3,604
Gains and Losses on Cash Flow Hedges
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	(493)	(557)	(444)	(529)
Other comprehensive income (loss) before reclassifications	(28)	18	(123)	(57)
Amounts reclassified from accumulated other comprehensive income (loss)	42	40	88	87
Other comprehensive income (loss), net of tax	14	58	(35)	30
Balance at the end of the period	(479)	(499)	(479)	(499)
Accumulated Other Comprehensive Income (Loss).
Accumulated Other Comprehensive Income (Loss)
Balance at the beginning of the period	3,505	2,998	(3,871)	(377)
Other comprehensive income (loss) before reclassifications	2,837	(5,108)	10,117	(1,920)
Amounts reclassified from accumulated other comprehensive income (loss)	168	179	264	366
Other comprehensive income (loss), net of tax	3,005	(4,929)	10,381	(1,554)
Balance at the end of the period	$ 6,510	$ (1,931)	$ 6,510	$ (1,931)