Loans (Details 12) (Commercial Loan [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	$ 2,894	$ 3,664
Construction and other real estate [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	1,906	2,185
Business banking and middle markets enterprises [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	610	698
Global banking [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	257	551
Other commercial [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	121	230
Special Mention [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	1,362	1,598
Special Mention [Member] | Construction and other real estate [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	805	1,009
Special Mention [Member] | Business banking and middle markets enterprises [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	447	445
Special Mention [Member] | Global banking [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	64	45
Special Mention [Member] | Other commercial [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	46	99
Substandard [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	1,295	1,759
Substandard [Member] | Construction and other real estate [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	969	990
Substandard [Member] | Business banking and middle markets enterprises [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	155	241
Substandard [Member] | Global banking [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	97	397
Substandard [Member] | Other commercial [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	74	131
Doubtful [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	237	307
Doubtful [Member] | Construction and other real estate [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	132	186
Doubtful [Member] | Business banking and middle markets enterprises [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	8	12
Doubtful [Member] | Global banking [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	96	109
Doubtful [Member] | Other commercial [Member]
Summary of criticized assets for commercial loans
Loans and leases doubtful receivable commercial net of deferred income	$ 1