Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Pre-Tax
Unrealized holding losses on securities	$ (571)	$ 12,520	$ (11,124)
Non-credit related portion of other-than-temporary impairment on securities	0	0	0
Reclassification adjustment for gains realized in net income(1)	(96)	(375)	115
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(178)	(253)	(348)
Total securities available for sale	(845)	11,892	(11,357)
Tax Expense (Benefit)
Unrealized holding losses on securities	(220)	4,789	(4,255)
Non-credit related portion of other-than-temporary impairment on securities	0	0	0
Reclassification adjustment for gains realized in net income(1)	(37)	(143)	44
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(68)	(97)	(133)
Total securities available for sale	(325)	4,549	(4,344)
Net of Tax
Unrealized holding (losses) gains on securities	(351)	7,731	(6,869)
Non-credit related portion of other-than-temporary impairment on securities	0	0	0
Reclassification adjustment for gains realized in net income(1)	(59)	(232)	71
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(110)	(156)	(215)
Total securities available for sale	(520)	7,343	(7,013)
Derivative Instruments, Pre-Tax [Abstract]
Unrealized holding gains on derivative instruments	(420)	(2,627)	2,146
Reclassification adjustment for gains realized in net income(2)	0	(2,627)	(203)
Total derivative instruments	(420)	0	1,943
Derivative Instruments, Tax Expense (Benefit) [Abstract]
Unrealized holding gains on derivative instruments	(171)	(1,005)	821
Reclassification adjustment for gains realized in net income(2)	0	(1,005)	(78)
Total derivative instruments	(171)	0	743
Derivative Instruments, Net of Tax [Abstract]
Unrealized holding (losses) gains on derivative instruments	(249)	(1,622)	1,325
Reclassification adjustment for gains realized in net income(2)	0	0	(125)
Total derivative instruments	(249)	(1,622)	1,200
Defined benefit pension and post-retirement benefit plans, Pre-Tax [Abstract]
Net gain arising during the period	(2,393)	(2,476)	3,170
Amortization of net actuarial loss recognized in net periodic pension cost(3)	432	296	622
Total defined benefit pension and post-retirement benefit plans	(1,961)	(2,180)	3,792
Defined benefit pension and post-retirement benefit plans, Tax Expense (Benefit) [Abstract]
Net gain arising during the period	(958)	(947)	1,213
Amortization of net actuarial loss recognized in net periodic pension cost(3)	165	113	238
Total defined benefit pension and post-retirement benefit plans	(793)	(834)	1,451
Defined benefit pension and post-retirement benefit plans, Net of Tax [Abstract]
Net gain arising during the period	(1,435)	(1,529)	1,957
Less amortization of net actuarial loss recognized in net periodic pension cost	267	183	384
Total defined benefit pension and post-retirement benefit plans	(1,168)	(1,346)	2,341
Total other comprehensive loss, Pre-Tax	(3,226)	7,085	(5,622)
Total other comprehensive loss, Tax Expense (Benefit)	(1,289)	2,710	(2,150)
Total other comprehensive income, Net of Tax	$ (1,937)	$ 4,375	$ (3,472)