Loans And Leases (Schedule Of Allowance For Loan Losses) (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011	Mar. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	$ 12,275	$ 10,053
Total allowance for loan losses	22	22	80	100
Institutional [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	11,815	9,593
Total allowance for loan losses	22	22	31	31
Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans and leases	460	460
Total allowance for loan losses	0		49	69
Loans And Leases [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	474	477
Collectively evaluated for impairment	11,762	9,537
Loans acquired with deteriorated credit quality	39	39
Loans And Leases [Member] | Institutional [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	53	56
Collectively evaluated for impairment	11,762	9,537
Loans acquired with deteriorated credit quality	0	0
Loans And Leases [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for impairment	421	421
Collectively evaluated for impairment	0	0
Loans acquired with deteriorated credit quality	$ 39	$ 39