Loans (Details 15) (USD $) In Millions, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Delinquency ratio for consumer loan
Dollars of Delinquency	$ 52	$ 53
Consumer Loan [Member]
Delinquency ratio for consumer loan
Dollars of Delinquency	1,220	1,258
Delinquency Ratio	6.18%	6.01%
Consumer Loan [Member] | Residential mortgages, excluding home equity mortgages [Member]
Delinquency ratio for consumer loan
Dollars of Delinquency	1,107	1,101
Delinquency Ratio	7.16%	7.19%
Consumer Loan [Member] | Home equity mortgages [Member]
Delinquency ratio for consumer loan
Dollars of Delinquency	62	99
Delinquency Ratio	2.33%	2.89%
Consumer Loan [Member] | Total residential mortgages [Member]
Delinquency ratio for consumer loan
Dollars of Delinquency	1,169	1,200
Delinquency Ratio	6.45%	6.41%
Consumer Loan [Member] | Credit card receivables [Member]
Delinquency ratio for consumer loan
Dollars of Delinquency	23	28
Delinquency Ratio	2.62%	2.25%
Consumer Loan [Member] | Other consumer [Member]
Delinquency ratio for consumer loan
Dollars of Delinquency	$ 28	$ 30
Delinquency Ratio	3.68%	3.17%