Loans Held for Sale (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	$ 1,809	$ 2,185
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	844	2,095
Commercial Loans [Member] | Commercial Real Estate [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	17	1,895
Commercial Loans [Member] | Global Banking [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	827	200
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	965	90
Consumer Loans [Member] | Residential Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	890	11
Consumer Loans [Member] | Home Equity Mortgages [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	4	0
Consumer Loans [Member] | Other consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans held for sale	$ 71	$ 79