Loans Held for Sale - Additional Information (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	$ 500	$ 230
Residential mortgage loans held for sale include subprime residential mortgage loans at fair value	23	46
Commercial Loan [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	396	76
Valuation allowance	7	0
Commercial Loans - Syndicated Fair Value Option [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	159	58
Commercial Loans - Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	43
Commercial Loans - Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	194	18
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	104	154
Valuation allowance	$ 46	$ 77