Net Interest Revenue (Components Of Interest Revenue And Interest Expenses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Net Interest Revenue [Abstract]
Deposits with banks	$ 35	$ 28	$ 77	$ 55
U.S. Treasury and federal agencies	206	198	405	404
State and political subdivisions	54	55	108	111
Other investments	406	364	811	719
Securities purchased under resale agreements	13	6	22	16
Loans and leases	71	67	126	147
Other interest-earning assets	1	1	2	1
Total interest revenue	786	719	1,551	1,453
Deposits	37	44	90	102
Short-term borrowings	19	24	37	51
Long-term debt	54	76	120	147
Other interest-bearing liabilities	4	3	7	4
Total interest expense	114	147	254	304
Net interest revenue	$ 672	$ 572	$ 1,297	$ 1,149