Loans And Leases (Narrative) (Details) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended	9 Months Ended	3 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010	Sep. 30, 2011 Institutional Loans [Member] days	Dec. 31, 2010 Institutional Loans [Member] days	Sep. 30, 2011 Commercial Real Estate [Member] days	Dec. 31, 2010 Commercial Real Estate [Member] days	Sep. 30, 2011 Property Development Loan [Member]	Mar. 31, 2011 Property Development Acquired Credit-Impaired [Member]	Sep. 30, 2011 Property Development Acquired Credit-Impaired [Member]	Sep. 30, 2011 Troubled Debt Restructuring [Member]
Aggregate short-duration advances	$ 3,810,000,000		$ 3,810,000,000		$ 2,630,000,000
Aggregate of debt restructurings	260,000,000		260,000,000		307,000,000								0
Impairment loss on restructuring of loans			0
Loans or leases contractually past-due	11,718,000,000		11,718,000,000		11,857,000,000	0	0
Loans or leases contractually past-due days						90	90	90	90
Recorded investment of property										52,000,000	42,000,000
Property carried at fair value										52,000,000	22,000,000
Allowance for loan losses, charge-offs	32,000,000	1,000,000	79,000,000	4,000,000						24,000,000	19,000,000
Other real estate owned										$ 52,000,000		$ 42,000,000