Interest and dividends on SAFS (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Schedule of Available-for-sale Securities [Line Items]
Interest Income, Securities, Taxable		$ 205	$ 184	$ 407	$ 364
Interest Income, Securities, Tax Exempt		5	3	9	5
Interest and Dividend Income, Securities, Available-for-sale	[1],[2]	$ 210	$ 187	$ 416	$ 369

[1] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets on the Consolidated Balance Sheets and began presenting income associated with certain of these equity securities in Trading account interest and other on the Consolidated Statements of Income. For periods prior to January 1, 2018, income associated with these equity securities was presented in Interest on securities available for sale and has been reclassified to Trading account interest and other for comparability.

[2] Beginning January 1, 2018, the Company reclassified equity securities previously presented in Securities available for sale to Other assets on the Consolidated Balance Sheets and began presenting income associated with certain of these equity securities in Trading account interest and other. For periods prior to January 1, 2018, income associated with these equity securities was presented in Interest on securities available for sale and has been reclassified to Trading account interest and other for comparability.