Discontinued Operations - Disposals That Do Not Qualify For Discontinued Operations Reporting (Details) (Disposal Group, Not Discontinued Operations [Member], GB&M London Precious Metals Custody and Clearing Business [Member], USD $)	0 Months Ended	3 Months Ended	12 Months Ended
	Dec. 19, 2014	Dec. 19, 2014	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Disposal Group, Not Discontinued Operations [Member] | GB&M London Precious Metals Custody and Clearing Business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Increase to additional paid-in capital due to sale of GB&M London precious metals business to an affiliate	$ 60,000,000
Decrease in trading assets		(3,000,000,000)
Decrease in Loans		(320,000,000)
Decrease in Deposits		(440,000,000)
Decrease in Short-term Borrowings		(370,000,000)
Decrease in trading liabilities		(3,000,000,000)
Income before taxes			$ 20,000,000	$ 30,000,000	$ 49,000,000