Other Comprehensive Income (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Securities available for sale:
Unrealized holding gains on securities, Pre-Tax	$ 4,025	$ 12,895	$ 7,439	$ 36,627
Non-credit related portion of other-than-temporary impairment on securities, Pre-Tax				(15,183)
Reclassification adjustment for gains realized in net income, Pre-Tax		(5,041)	(1,773)	(4,795)
Total securities available for sale, Pre-Tax	3,891	7,659	5,219	15,822
Unrealized holding gains on securities, Tax Expense (Benefit)	1,539	4,932	2,845	14,009
Non-credit related portion of other-than-temporary impairment on securities, Tax Expense (Benefit)				(5,807)
Reclassification adjustment for gains realized in net income, Tax Expense (Benefit)		(1,928)	(678)	(1,834)
Total securities available for sale, Tax Expense (Benefit)	1,488	2,930	1,996	6,052
Unrealized holding gains on securities	2,486	7,963	4,594	22,618
Non-credit related portion of other-than-temporary impairment on securities				(9,376)
Reclassification adjustment for gains realized in net income		(3,113)	(1,095)	(2,961)
Total securities available for sale	2,403	4,729	3,223	9,770
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Pre-Tax	(134)	(195)	(447)	(827)
Amortization of unrealized holding gains on securities transferred to the held to maturity category, Tax Expense (Benefit)	(51)	(74)	(171)	(316)
Amortization of unrealized holding gains on securities transferred to the held to maturity category	(83)	(121)	(276)	(511)
Derivative instruments:
Unrealized holding losses on derivative instruments, Pre-Tax	(391)		(2,234)
Reclassification adjustment for gains realized in net income, Pre-Tax	(115)	(154)	(419)	(457)
Total derivative instruments, Pre-Tax	(506)	(154)	(2,653)	(457)
Unrealized holding losses on derivative instruments, Tax Expense (Benefit)	(150)		(855)
Reclassification adjustment for gains realized in net income, Tax Expense (Benefit)	(44)	(59)	(160)	(175)
Total derivative instruments, Tax Expense (Benefit)	(194)	(59)	(1,015)	(175)
Unrealized holding losses on derivative instruments	(241)		(1,379)
Reclassification adjustment for gains realized in net income	(71)	(95)	(259)	(282)
Totals derivative instruments	(312)	(95)	(1,638)	(282)
Defined benefit pension and post-retirement benefit plans:
Net gain (loss) arising during the period, Pre-Tax
Net gain (loss) arising during the period, Tax Expense (Benefit)
Net gain (loss) arising during the period
Total defined benefit pension and post-retirement benefit plans, Pre-Tax	107	111	321	333
Amortization of net actuarial loss recognized in net periodic pension cost, Pre-Tax	107	111	321	333
Total defined benefit pension and post-retirement benefit plans, Tax Expense (Benefit)	41	42	123	127
Amortization of net actuarial loss recognized in net periodic pension cost, Tax Expense (Benefit)	41	42	123	127
Total defined benefit pension and post-retirement benefit plans	66	69	198	206
Less amortization of net actuarial loss recognized in net periodic pension cost	66	69	198	206
Total other comprehensive income, Pre-Tax	3,492	7,616	2,887	15,698
Total other comprehensive income, Tax Expense (Benefit)	1,335	2,913	1,104	6,004
Other comprehensive income, net of tax	$ 2,157	$ 4,703	$ 1,783	$ 9,694