Employee Compensation and Benefit Plans - Schedule of Restricted Stock and Unit Awards and Performance Restricted Stock Units Activity (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Aggregate Intrinsic Value
Taxes paid related to net share settlement of stock awards	$ 146	$ 166	$ 121
Minimum
Aggregate Intrinsic Value
Share payout percentage	0.00%
Maximum
Aggregate Intrinsic Value
Share payout percentage	200.00%
Restricted Stock and Unit Awards
Number of Units or Awards
Nonvested, beginning (in shares)	12,061,608
Granted (in shares)	6,259,169
Vested (in shares)	6,455,617
Forfeited (in shares)	854,525
Nonvested, ending (in shares)	11,010,635	12,061,608
Weighted Average Grant Date Fair Value
Nonvested, beginning (in USD per share)	$ 50.69
Granted (in USD per share)	60.44
Vested (in USD per share)	47.89
Forfeited (in USD per share)	56.90
Nonvested, ending (in USD per share)	$ 57.66	$ 50.69
Weighted Average Remaining Contractual Term (Years)
Nonvested, Weighted Average Remaining Contractual Term, beginning (in years)	11 months 16 days	1 year 1 month 6 days
Nonvested, Weighted Average Remaining Contractual Term, ending (in years)	11 months 16 days	1 year 1 month 6 days
Aggregate Intrinsic Value
Nonvested, Aggregate Intrinsic Value, beginning	$ 700	$ 766
Nonvested, Aggregate Intrinsic Value, ending	$ 700	$ 766
Performance Restricted Stock Units
Number of Units or Awards
Nonvested, beginning (in shares)	1,633,935
Granted (in shares)	3,364,629
Vested (in shares)	1,006,769
Forfeited (in shares)	140,241
Nonvested, ending (in shares)	3,851,554	1,633,935
Weighted Average Grant Date Fair Value
Nonvested, beginning (in USD per share)	$ 48.06
Granted (in USD per share)	63.54
Vested (in USD per share)	36.47
Forfeited (in USD per share)	64.14
Nonvested, ending (in USD per share)	$ 64.03	$ 48.06
Weighted Average Remaining Contractual Term (Years)
Nonvested, Weighted Average Remaining Contractual Term, beginning (in years)	1 year 6 months 26 days	1 year 1 month 6 days
Nonvested, Weighted Average Remaining Contractual Term, ending (in years)	1 year 6 months 26 days	1 year 1 month 6 days
Aggregate Intrinsic Value
Nonvested, Aggregate Intrinsic Value, beginning	$ 245	$ 104
Nonvested, Aggregate Intrinsic Value, ending	$ 245	$ 104
Restricted Stock Units and Performance Stock Units
Weighted Average Grant Date Fair Value
Granted (in USD per share)	$ 61.52	$ 60.21	$ 45.07
Aggregate Intrinsic Value
Shares paid for tax withholding for share based compensation (in shares)	2,321,827	2,754,721