Other Comprehensive Income - (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Securities:
Unrealized holding gains on securities, Pre-Tax	$ 4,249	$ 4,509
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Pre-Tax	(51)	(71)
Total securities available for sale, Pre-Tax	4,198	4,438
Unrealized holding gains on securities, Tax Expense (Benefit)	1,625	1,725
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Tax Expense (Benefit)	(19)	(27)
Total securities available for sale, Tax Expense (Benefit)	1,606	1,698
Unrealized holding gains on securities	2,624	2,784
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(32)	(44)
Total securities	2,592	2,740
Derivative instruments:
Unrealized holding losses on derivative instruments, Pre-Tax	(1,084)	(679)
Total derivative instruments, Pre-Tax	(1,084)	(679)
Unrealized holding gains on derivative instruments, Tax Expense (Benefit)	(415)	(260)
Total derivative instruments, Tax Expense (Benefit)	(415)	(260)
Unrealized holding gains (losses) on derivative instruments	(669)	(419)
Totals derivative instruments	(669)	(419)
Defined benefit pension and post-retirement benefit plans:
Amortization of net actuarial loss recognized in net periodic pension cost, Pre-Tax	93	73
Total defined benefit pension and post-retirement benefit plans, Pre-Tax	93	73
Amortization of net actuarial loss recognized in net periodic pension cost, Tax Expense (Benefit)	36	28
Total defined benefit pension and post-retirement benefit plans, Tax Expense (Benefit)	36	28
Less amortization of net actuarial loss recognized in net periodic pension cost	57	45
Total defined benefit pension and post-retirement benefit plans	57	45
Total other comprehensive income, Pre-Tax	3,207	3,832
Total other comprehensive income, Tax Expense (Benefit)	1,227	1,466
Other comprehensive income, net of tax	$ 1,980	$ 2,366