Loans (Details 5) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	$ 1,334	$ 1,282
Commercial loans [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	546	580
Commercial loans [Member] | Construction and other real estate [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	374	393
Commercial loans [Member] | Business banking and middle markets enterprises [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	135	147
Commercial loans [Member] | Global banking [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans
Commercial loans [Member] | Other commercial [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	37	40
Consumer loans [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	788	702
Consumer loans [Member] | Residential mortgages [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	770	682
Consumer loans [Member] | Credit cards [Member]
Unpaid principal balance trouble debt restructuring
Unpaid Principal Balance of TDR Loans	$ 18	$ 20