Statements of Income/(Loss) - Parent Company Only (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest and Dividend Income, Securities, Available-for-sale		$ 651	$ 593	$ 613
Trading Gain (Loss)		211	181	182
Gain (Loss) on Disposition of Business		0	0	105
Interest Expense, Long-term Debt		260	252	270
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		2,692	2,707	2,278
Income Tax Expense (Benefit)		(805)	(764)	(493)
Net Income (Loss) Attributable to Parent		1,878	1,933	1,774
Dividends, Preferred Stock, Cash	[1]	(66)	(64)	(42)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic		(1)	(6)	(10)
Net Income (Loss) Available to Common Stockholders, Basic		1,811	1,863	1,722
Parent Company [Member]
Interest and Dividend Income, Securities, Available-for-sale	[2]	1,300	1,159	1,057
Interest and Fee Income, Other Loans		15	8	7
Trading Gain (Loss)		2	(1)	10
Gain (Loss) on Disposition of Business		0	0	105
Other Income		12	15	13
Revenues		1,329	1,181	1,192
Interest Expense, Short-term Borrowings		2	1	7
Interest Expense, Long-term Debt		140	128	122
Labor and Related Expense	[3]	57	69	42
Fees and Commission Expense		12	6	10
Other Expenses		24	21	11
Operating Expenses		235	225	192
Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest		1,094	956	1,000
Income Tax Expense (Benefit)		59	61	2
Income (Loss) Before Equity in Undistributed Earnings of Subsidiaries		1,153	1,017	1,002
Equity in Undistributed Earnings of Subsidiaries		725	916	772
Net Income (Loss) Attributable to Parent		1,878	1,933	1,774
Dividends, Preferred Stock, Cash		(66)	(64)	(42)
Undistributed Earnings (Loss) Allocated to Participating Securities, Basic		(1)	(6)	(10)
Net Income (Loss) Available to Common Stockholders, Basic		$ 1,811	$ 1,863	$ 1,722

[1] For the year ended December 31, 2016, dividends were $4,067 per share for both Perpetual Preferred Stock Series A and B, $5,875 per share for Perpetual Preferred Stock Series E, and $5,625 per share for Perpetual Preferred Stock Series F.For the year ended December 31, 2015, dividends were $4,056 per share for both Perpetual Preferred Stock Series A and B, $5,875 per share for Perpetual Preferred Stock Series E, and $6,219 per share for Perpetual Preferred Stock Series F.

[2] Substantially all dividend income is from subsidiaries (primarily the Bank).

[3] Includes incentive compensation allocations between the Parent Company and subsidiaries.