Derivative And Credit-Related Financial Instruments (Narrative) (Details) (USD $) Share data in Thousands, unless otherwise specified	3 Months Ended			9 Months Ended
	Sep. 30, 2011	Mar. 31, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Percentage of derivative contracts in an unrealized gain position with bilateral collateral agreements secured by marketable investment securities	90.00%			90.00%
Aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	$ 120,000,000			$ 120,000,000
Collateral pledged for aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	105,000,000			105,000,000
Cash collateral pledged for aggregate fair value of all derivative instruments with credit-risk contingent features that were in a liability position	1,000,000			1,000,000
Additional required overnight collateral on derivatives with credit-risk contingent features at period end should the credit-risk contingent features be triggered	15,000,000			15,000,000
Net interest income generated by risk management fair value interest rate swaps	18,000,000		19,000,000	54,000,000	58,000,000
Notional amount of interest rate swap agreements under a cash flow hedging strategy that matured during the period		800,000,000
Net gains recognized in other noninterest income for customer-initiated foreign exchange contracts not offset by the Corporation	1,000,000			1,000,000	1,000,000
Allowance for credit losses on lending-related commitments	27,000,000			27,000,000		35,000,000
Remaining fair value adjustment for unfunded commitments and letters of credit	4,000,000			4,000,000
Allowance for credit losses on lending-related commitments, unused commitments to extend credit	10,000,000			10,000,000		16,000,000
Latest year of contract expiration on standby and commercial letters of credit	2021			2021
Risk participation agreements covering standby and commercial letters of credit	258,000,000			258,000,000		298,000,000
Standby and commercial letters of credit	5,400,000,000			5,400,000,000		5,500,000,000
Carrying value of standby and commercial letters of credit included in accrued expenses and other liabilities	89,000,000			89,000,000		83,000,000
Deferred fees	72,000,000			72,000,000		64,000,000
Allowance for credit losses on lending-related commitments, standby and commercial letters of credit	17,000,000			17,000,000		19,000,000
Total notional amount of the credit risk participation agreements	370,000,000			370,000,000		316,000,000
Maximum estimated exposure to credit risk participation agreements assuming 100% default	13,000,000			13,000,000		12,000,000
Weighted average remaining maturity of credit risk participation agreements, in years	2.4			2.4
Notional amount of the derivative contract equivalent to Visa Class B shares	780			780
Fair value of Visa Class B derivative contract	1,000,000			1,000,000		1,000,000
Sterling [Member]
Allowance for credit losses on lending-related commitments	$ 0			$ 0