Other Comprehensive Income - (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Securities:
Unrealized holding gains on securities, Pre Tax	$ 6,029	$ 1,402	$ 4,066	$ 7,864
Reclassification adjustment for gains realized in net income, Pre Tax	0	(375)	(96)	(375)
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Pre Tax	(42)	(61)	(139)	(196)
Total securities available for sale, Pre Tax	5,987	966	3,831	7,293
Unrealized holding gains on securities, Tax Expense (Benefit)	2,312	536	1,561	3,008
Reclassification adjustment for gains realized in net income, Tax Expense (Benefit)	0	(143)	(36)	(143)
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Tax Expense (Benefit)	(16)	(23)	(53)	(75)
Total securities available for sale, Tax Expense (Benefit)	2,296	370	1,472	2,790
Net change in unrealized holding gains on securities	3,717	866	2,505	4,856
Reclassification adjustment for gains realized in net income	0	(232)	(60)	(232)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(26)	(38)	(86)	(121)
Total securities	3,691	596	2,359	4,503
Derivative instruments:
Unrealized holding losses on derivative instruments, Pre-Tax	(1,752)	68	(1,437)	(1,252)
Total derivative instruments, Pre-Tax	(1,752)	68	(1,437)	(1,252)
Unrealized holding gains on derivative instruments, Tax Expense (Benefit)	(677)	26	(556)	(479)
Total derivative instruments, Tax Expense (Benefit)	(677)	26	(556)	(479)
Unrealized holding gains (losses) on derivative instruments	(1,075)	42	(881)	(773)
Totals derivative instruments	(1,075)	42	(881)	(773)
Defined benefit pension and post-retirement benefit plans:
Amortization of net actuarial loss recognized in net periodic pension cost, Pre-Tax	114	76	316	222
Total defined benefit pension and post-retirement benefit plans, Pre-Tax	114	76	316	222
Amortization of net actuarial loss recognized in net periodic pension cost, Tax Expense (Benefit)	59	29	136	85
Total defined benefit pension and post-retirement benefit plans, Tax Expense (Benefit)	59	29	136	85
Less amortization of net actuarial loss recognized in net periodic pension cost	55	47	180	137
Total defined benefit pension and post-retirement benefit plans	55	47	180	137
Total other comprehensive income, Pre-Tax	4,349	1,110	2,710	6,263
Total other comprehensive income, Tax Expense (Benefit)	1,678	425	1,052	2,396
Other comprehensive income, net of tax	$ 2,671	$ 685	$ 1,658	$ 3,867