Loans (Details 7) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
	Jun. 30, 2012	Jun. 30, 2012
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent	$ 7	$ 13
Commercial loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent
Consumer loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent	7	13
Construction and other real estate [Member] | Commercial loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent
Business banking and middle markets enterprises [Member] | Commercial loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent
Global banking [Member] | Commercial loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent
Other commercial [Member] | Commercial loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent
Residential mortgages [Member] | Consumer loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent	7	13
Credit cards [Member] | Consumer loans [Member]
Commercial loans and Consumer loans classified as TDR Loans
TDR loans during previous months which became contractually delinquent