Derivatives (Derivatives Associated With Interest Rate Risk Management Activities) (Details) (USD $) In Thousands, unless otherwise specified						3 Months Ended				9 Months Ended						3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended				3 Months Ended				9 Months Ended
	Sep. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Sep. 30, 2012 Customer Interest Rate Contracts [Member]	Sep. 30, 2011 Customer Interest Rate Contracts [Member]	Sep. 30, 2012 Customer Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2011 Customer Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2012 Customer Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2011 Customer Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2012 Offsetting Upstream Interest Rate Contracts [Member]	Sep. 30, 2011 Offsetting Upstream Interest Rate Contracts [Member]	Sep. 30, 2012 Offsetting Upstream Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2011 Offsetting Upstream Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2012 Offsetting Upstream Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2011 Offsetting Upstream Interest Rate Contracts [Member] Customer Interest Rate Contracts Hedging [Member] Hedging Instruments And Hedged Items [Member]		Sep. 30, 2012 Interest Rate Swap [Member] Debt [Member] Hedging Instruments [Member]		Sep. 30, 2011 Interest Rate Swap [Member] Debt [Member] Hedging Instruments [Member]		Sep. 30, 2012 Interest Rate Swap [Member] Debt [Member] Hedging Instruments [Member]		Sep. 30, 2011 Interest Rate Swap [Member] Debt [Member] Hedging Instruments [Member]		Sep. 30, 2012 Long Term Debt [Member] Debt [Member] Hedged Items [Member]		Sep. 30, 2011 Long Term Debt [Member] Debt [Member] Hedged Items [Member]		Sep. 30, 2012 Long Term Debt [Member] Debt [Member] Hedged Items [Member]		Sep. 30, 2011 Long Term Debt [Member] Debt [Member] Hedged Items [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional				$ 1,439,306	$ 1,438,750	$ 975,213	[1]	$ 1,048,686	[1]	$ 975,213	[1]	$ 1,048,686	[1]	$ 1,439,306	$ 1,438,750	$ 975,213	[1]	$ 1,048,686	[1]	$ 975,213	[1]	$ 1,048,686	[1]	$ 1,604,000	[2]	$ 1,604,000	[2]	$ 1,604,000	[2]	$ 1,604,000	[2]
Assets				137,958	120,529	61,984	[1]	77,297	[1]	61,984	[1]	77,297	[1]	923	1,521	362	[1]	514	[1]	362	[1]	514	[1]	111,240	[2]	137,786	[2]	111,240	[2]	137,786	[2]
Liabilities				923	1,521	362	[1]	514	[1]	362	[1]	514	[1]	137,958	120,529	63,384	[1]	79,797	[1]	63,384	[1]	79,797	[1]	0	[2]	0	[3]	0	[2]	0	[3]
Gains/(Losses)						(3,971)	[1]	11,532	[1]	(7,554)	[1]	4,636	[1]			4,071	[1]	(11,923)	[1]	8,254	[1]	(4,929)	[1]	(2,481)	[2]	36,748	[2]	(15,642)	[2]	40,110	[2]
Term borrowings	2,263,238	2,481,660	2,509,804																													1,604,000	[2],[4]	1,604,000	[2],[4]	1,604,000	[2],[4]	1,604,000	[2],[4]
Gains/(Losses) related to term borrowings																																$ 2,481	[2],[5]	$ (36,748)	[2],[5]	$ 15,642	[2],[5]	$ (40,110)	[2],[5]

[1] Gains/losses included in the Other expense section of the Consolidated Condensed Statements of Income.

[2] Gains/losses included in the All other income and commissions section of the Consolidated Condensed Statements of Income.

[3] Represents principal balance being hedged.

[4] Represents par value of term borrowings being hedged.

[5] Represents gains and losses attributable to changes in fair value due to interest rate risk as designated in ASC 815-20 hedging relationships.