Other Comprehensive Income (Details) (USD $)	3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended				9 Months Ended		9 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Equity Securities [Member]	Sep. 30, 2010 Equity Securities [Member]	Sep. 30, 2011 Equity Securities [Member]	Sep. 30, 2010 Equity Securities [Member]	Sep. 30, 2011 Debt Securities [Member]	Sep. 30, 2010 Debt Securities [Member]	Sep. 30, 2011 Debt Securities [Member]	Sep. 30, 2010 Debt Securities [Member]	Sep. 30, 2010 Unrealized gains and losses on debt securities [Member]	Dec. 31, 2010 Unrealized gains and losses on debt securities [Member]	Sep. 30, 2010 Unrealized gains and losses on equity securities [Member]	Dec. 31, 2010 Unrealized gains and losses on equity securities [Member]	Sep. 30, 2010 Unrealized gains and losses on cash flow hedging derivatives [Member]	Dec. 31, 2010 Unrealized gains and losses on cash flow hedging derivatives [Member]	Sep. 30, 2010 Accumulated Unrealized Losses for Pension and Other Post-retirement obligations [Member]	Dec. 31, 2010 Accumulated Unrealized Losses for Pension and Other Post-retirement obligations [Member]
Pretax
Cumulative effect of change in accounting principle for consolidation of variable interest entities pretax												$ (6,365,000)
Non-credit-related impairment losses (recoveries) on debt (equity) securities not expected to be sold, pretax									4,362,000	30,492,000	11,079,000	36,570,000
Unrealized holding gains (losses) on debt (equity) securities available for sale arising during the period, pretax									42,832,000	28,767,000	132,575,000	137,051,000
Less: Reclassification adjustment for net losses (gains) losses included in net income, pretax									1,350,000	296,000	(197,000)	171,000
Net change in unrealized holding gains (losses) on debt (equity) securities available for sale, pretax					(197,000)	(53,000)	(145,000)	(241,000)	39,820,000	59,555,000	143,457,000	173,792,000
Unrealized gains and losses on derivatives used in cash flow hedging relationships arising during the period, pretax	21,494,000	25,180,000	24,897,000	26,371,000
Change in pension and post-retirement benefit plan assets and liabilities, pretax	4,003,000	1,794,000	12,003,000	5,382,000
Total other comprehensive income (loss), pretax	65,120,000	86,476,000	180,212,000	198,939,000
Tax (Expense) Benefit
Cumulative effect of change in accounting principle for consolidation of variable interest entities, tax (expense) benefit												2,116,000
Non-credit-related impairment losses (recoveries) on debt (equity) securities not expected to be sold, tax (expense) benefit									1,527,000	(10,672,000)	(3,878,000)	(12,799,000)
Unrealized holding gains (losses) on debt (equity) securities available for sale arising during the period, tax (expense) benefit									(15,180,000)	(10,276,000)	(46,446,000)	(48,578,000)
Less: Reclassification adjustment for net losses (gains) losses included in net income, tax (expense) benefit									(473,000)	(104,000)	69,000	(60,000)
Net change in unrealized holding gains (losses) on debt (equity) securities available for sale, tax (expense) benefit					69,000	19,000	50,000	85,000	(14,126,000)	(21,052,000)	(50,255,000)	(61,437,000)
Unrealized gains and losses on derivatives used in cash flow hedging relationships arising during the period, tax (expense) benefit	(7,523,000)	(8,813,000)	(8,714,000)	(9,230,000)
Change in pension and post-retirement benefit plan assets and liabilities, tax (expense) benefit	(1,401,000)	(628,000)	(4,201,000)	(1,884,000)
Total other comprehensive income (loss), tax (expense) benefit	(22,981,000)	(30,474,000)	(63,120,000)	(70,350,000)
After-tax
Cumulative effect of change in accounting principle for consolidation of variable interest entities, after-tax				(4,249,000)								(4,249,000)	(4,249,000)		0		0		0
Non-credit-related impairment losses (recoveries) on debt (equity) securities not expected to be sold, after-tax									(2,835,000)	19,820,000	7,201,000	23,771,000
Unrealized holding gains (losses) on debt (equity) securities available for sale arising during the period, after-tax									27,652,000	18,491,000	86,129,000	88,473,000
Less: Reclassification adjustment for net losses (gains) losses included in net income, after-tax									877,000	192,000	(128,000)	111,000
Net change in unrealized holding gains (losses) on debt (equity) securities available for sale, after-tax			85,906,000	88,428,000	(128,000)	(34,000)	(95,000)	(156,000)	25,694,000	38,503,000	93,202,000	112,355,000
Unrealized gains and losses on derivatives used in cash flow hedging relationships arising during the period, after-tax	13,971,000	16,367,000	16,183,000	17,141,000
Change in pension and post-retirement benefit plan assets and liabilities, after-tax	2,602,000	1,166,000	7,802,000	3,498,000
Total other comprehensive income (loss), after-tax	42,139,000	56,002,000	117,092,000	128,589,000
Activity in accumulated other comprehensive income, net of tax
Beginning Balance			(197,496,000)	(156,985,000)									(103,060,000)	(101,290,000)	(322,000)	(427,000)	58,865,000	35,710,000	(112,468,000)	(131,489,000)
Cumulative effect of change in accounting principle for consolidation of variable interest entities				(4,249,000)								(4,249,000)	(4,249,000)		0		0		0
Period change				132,838,000									112,355,000		(156,000)		17,141,000		3,498,000
Ending Balance	(80,404,000)	(28,396,000)	(80,404,000)	(28,396,000)									5,046,000	(101,290,000)	(478,000)	(427,000)	76,006,000	35,710,000	(108,970,000)	(131,489,000)
Other Comprehensive Income (Textual) [Abstract]
Unrealized losses transferred from the available for sale securities portfolio to the held to maturity securities	$ 400,000		$ 400,000