Loans (Details 8) (Commercial loans [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Impaired commercial loan statistic
Amount With Impairment Reserves	$ 421	$ 597
Amount Without Impairment Reserves	486	490
Total Impaired Commercial Loans	907	1,087
Impaired Reserve	132	216
Construction and other real estate [Member]
Impaired commercial loan statistic
Amount With Impairment Reserves	267	391
Amount Without Impairment Reserves	324	342
Total Impaired Commercial Loans	591	733
Impaired Reserve	111	114
Business banking and middle markets enterprises [Member]
Impaired commercial loan statistic
Amount With Impairment Reserves	55	68
Amount Without Impairment Reserves	60	59
Total Impaired Commercial Loans	115	127
Impaired Reserve	7	12
Global banking [Member]
Impaired commercial loan statistic
Amount With Impairment Reserves	96	137
Amount Without Impairment Reserves	18
Total Impaired Commercial Loans	114	137
Impaired Reserve	13	90
Other commercial [Member]
Impaired commercial loan statistic
Amount With Impairment Reserves	3	1
Amount Without Impairment Reserves	84	89
Total Impaired Commercial Loans	87	90
Impaired Reserve	$ 1