Derivative Financial Instruments Netting of Financial Instruments - Derivatives (Details) - USD ($) $ in Millions		Jun. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		$ 3,518	$ 2,631
Derivative Asset, Fair Value, Gross Asset Including Not Subject to Master Netting Arrangement		3,518	2,631
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		2,061	1,992
Derivative Asset	[1]	1,457	639
Derivative, Collateral, Obligation to Return Securities		14	12
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		1,443	627
Derivative Liability, Fair Value, Gross Liability		2,857	2,716
Derivative Liability, Fair Value, Gross Liability Including Not Subject to Master Netting Arrangement		2,857	2,716
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		2,651	2,306
Derivative Liability	[2]	206	410
Derivative, Collateral, Right to Reclaim Securities		26	14
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		180	396
Derivatives Subject to Master Netting Arrangement or Similar Arrangement [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		3,007	2,425
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		1,944	1,873
Derivative Asset		1,063	552
Derivative, Collateral, Obligation to Return Securities		13	12
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		1,050	540
Derivative Liability, Fair Value, Gross Liability		2,638	2,521
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		2,534	2,187
Derivative Liability		104	334
Derivative, Collateral, Right to Reclaim Securities		15	14
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		89	320
Derivatives Not Subject to Master Netting Arrangement or Similar Arrangement [Member] [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		112	20
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		0	0
Derivative Asset		112	20
Derivative, Collateral, Obligation to Return Securities		1	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		111	20
Derivative Liability, Fair Value, Gross Liability		102	76
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		0	0
Derivative Liability		102	76
Derivative, Collateral, Right to Reclaim Securities		11	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		91	76
Exchange Traded [Member]
Derivative [Line Items]
Derivative Asset, Fair Value, Gross Asset		399	186
Derivative Asset, Fair Value, Gross Liability and Obligation to Return Cash, Offset		117	119
Derivative Asset		282	67
Derivative, Collateral, Obligation to Return Securities		0	0
Derivative Asset, Fair Value, Amount Not Offset Against Collateral		282	67
Derivative Liability, Fair Value, Gross Liability		117	119
Derivative Liability, Fair Value, Gross Asset and Right to Reclaim Cash, Offset		117	119
Derivative Liability		0	0
Derivative, Collateral, Right to Reclaim Securities		0	0
Derivative Liability, Fair Value, Amount Not Offset Against Collateral		$ 0	$ 0

[1] At June 30, 2019, $1.5 billion, net of $328 million offsetting cash collateral, is recognized in Trading assets and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2018, $639 million, net of $338 million offsetting cash collateral, is recognized in Trading assets and derivative instruments within the Company's Consolidated Balance Sheets.

[2] At June 30, 2019, $206 million, net of $918 million offsetting cash collateral, is recognized in Trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets. At December 31, 2018, $410 million, net of $652 million offsetting cash collateral, is recognized in Trading liabilities and derivative instruments within the Company's Consolidated Balance Sheets.