Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Pre-Tax
Unrealized holding gains on securities	$ 12,520	$ (11,124)	$ 5,351
Non-credit related portion of other-than-temporary impairment on securities	0	0	0
Reclassification adjustment for gains realized in net income	(375)	115	(1,894)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(253)	(348)	(567)
Total securities available for sale	11,892	(11,357)	2,890
Tax Expense (Benefit)
Unrealized holding gains on securities	(4,789)	(4,255)	2,046
Non-credit related portion of other-than-temporary impairment on securities	0	0	0
Reclassification adjustment for gains realized in net income	143	44	(724)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	97	(133)	(217)
Total securities available for sale	(4,549)	(4,344)	1,105
Net of Tax
Unrealized holding gains (losses) on securities	7,731	(6,869)	3,305
Non-credit related portion of other-than-temporary impairment on securities	0	0	0
Reclassification adjustment for gains realized in net income	(232)	71	(1,170)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(156)	(215)	(350)
Total securities available for sale	7,343	(7,013)	1,785
Derivative Instruments, Pre-Tax [Abstract]
Unrealized holding losses on derivative instruments	(2,627)	1,943	(2,164)
Reclassification adjustment for gains realized in net income	0	2,146	(503)
Total derivative instruments	(2,627)	(203)	(2,667)
Derivative Instruments, Tax Expense (Benefit) [Abstract]
Unrealized holding losses on derivative instruments	1,005	743	(828)
Reclassification adjustment for gains realized in net income	0	821	(192)
Total derivative instruments	1,005	(78)	(1,020)
Derivative Instruments, Net of Tax [Abstract]
Unrealized holding (losses) gains on derivative instruments	(1,622)	1,325	(1,336)
Reclassification adjustment for gains realized in net income	0	(125)	(311)
Totals derivative instruments	(1,622)	1,200	(1,647)
Defined benefit pension and post-retirement benefit plans, Pre-Tax [Abstract]
Net loss arising during the period	(2,476)	3,170	(1,225)
Amortization of net actuarial loss recognized in net periodic pension cost	296	622	428
Total defined benefit pension and post-retirement benefit plans	(2,180)	3,792	(797)
Defined benefit pension and post-retirement benefit plans, Tax Expense (Benefit) [Abstract]
Net loss arising during the period	947	1,213	(469)
Amortization of net actuarial loss recognized in net periodic pension cost	113	(238)	(164)
Total defined benefit pension and post-retirement benefit plans	834	1,451	(305)
Defined benefit pension and post-retirement benefit plans, Net of Tax [Abstract]
Net loss arising during the period	(1,529)	1,957	(756)
Less amortization of net actuarial loss recognized in net periodic pension cost	183	384	264
Total defined benefit pension and post-retirement benefit plans	(1,346)	2,341	(492)
Total other comprehensive loss, Pre-Tax	7,085	(5,622)	(574)
Total other comprehensive loss, Tax Expense (Benefit)	(2,710)	(2,150)	(220)
Total other comprehensive income, Net of Tax	$ 4,375	$ (3,472)	$ (354)