Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Securities:
Unrealized holding gains on securities, Pre-Tax	$ 11,369	$ (1,766)	$ 11,133	$ (3,414)
Non-credit related portion of other-than-temporary impairment on securities, Pre-Tax	0	0	0	0
Reclassification adjustment for losses realized in net income, Pre-Tax	0	869	(115)	1,773
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Pre-Tax	(88)	(148)	(194)	(313)
Total securities available for sale, Pre-Tax	(11,457)	749	(11,212)	1,328
Unrealized holding gains on securities, Tax Expense (Benefit)	4,350	(676)	4,260	(1,306)
Non-credit related portion of other-than-temporary impairment on securities, Tax Expense (Benefit)	0	0	0	0
Reclassification adjustment for gains realized in net income, Tax Expense (Benefit)	0	332	(44)	678
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Tax Expense (Benefit)	(34)	(57)	(74)	(120)
Total securities available for sale, Tax Expense (Benefit)	(4,384)	287	(4,290)	508
Unrealized holding gains on securities	(7,019)	1,090	(6,873)	2,108
Non-credit related portion of other-than-temporary impairment on securities	0	0	0	0
Reclassification adjustment for losses (gains) realized in net income	0	(537)	71	(1,095)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(54)	(91)	(120)	(193)
Total securities	(7,073)	462	(6,922)	820
Derivative instruments:
Unrealized holding losses on derivative instruments, Pre-Tax	1,607	(1,664)	1,942	(1,843)
Reclassification adjustment for gains realized in net income, Pre-Tax	(83)	(152)	(168)	(304)
Total derivative instruments, Pre-Tax	1,524	(1,816)	1,774	(2,147)
Unrealized holding gains on derivative instruments, Tax Expense (Benefit)	615	(637)	743	(705)
Reclassification adjustment for gains realized in net income, Tax Expense (Benefit)	(32)	(58)	(64)	(116)
Total derivative instruments, Tax Expense (Benefit)	583	(695)	679	(821)
Unrealized holding gains (losses) on derivative instruments	992	(1,027)	1,199	(1,138)
Reclassification adjustment for gains realized in net income	(51)	(94)	(104)	(188)
Totals derivative instruments	941	(1,121)	1,095	(1,326)
Defined benefit pension and post-retirement benefit plans:
Net gain (loss) arising during the period, Pre-Tax	0	0	0	0
Amortization of net actuarial loss recognized in net periodic pension cost, Pre-Tax	138	107	254	214
Total defined benefit pension and post-retirement benefit plans, Pre-Tax	138	107	254	214
Net gain (loss) arising during the period, Tax Expense (Benefit)	0	0	0	0
Amortization of net actuarial loss recognized in net periodic pension cost, Tax Expense (Benefit)	53	41	97	82
Total defined benefit pension and post-retirement benefit plans, Tax Expense (Benefit)	53	41	97	82
Net (loss) gain arising during the period	0	0	0	0
Less amortization of net actuarial loss recognized in net periodic pension cost	(85)	(66)	(157)	(132)
Total defined benefit pension and post-retirement benefit plans	(85)	(66)	(157)	(132)
Total other comprehensive income, Pre-Tax	(9,795)	(960)	(9,184)	(605)
Total other comprehensive income, Tax Expense (Benefit)	(3,748)	(367)	(3,514)	(231)
Other comprehensive loss, net of tax	$ (6,047)	$ (593)	$ (5,670)	$ (374)