Fair Value Measurement - Level 3 Analysis (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Level 3 Analysis - Supplemental Data [Abstract]
Percentage of level 3 assets in total Firm assets	0.50%
Recurring
Level 3 Analysis - Supplemental Data [Abstract]
Assets fair value	$ 1,243,209	$ 802,830
Recurring | Level 3
Level 3 Analysis - Supplemental Data [Abstract]
Assets fair value	16,410	$ 13,543
Increase (decrease) in level 3 assets	2,900
Recurring | Level 3 | Derivative receivables | Interest rate
Level 3 Analysis - Supplemental Data [Abstract]
Increase (decrease) in level 3 assets	907
Recurring | Level 3 | Derivative receivables | Equity
Level 3 Analysis - Supplemental Data [Abstract]
Increase (decrease) in level 3 assets	1,400
Recurring | Level 3 | Nontrading loans
Level 3 Analysis - Supplemental Data [Abstract]
Increase (decrease) in level 3 assets	1,800
Recurring | Level 3 | MSRs
Level 3 Analysis - Supplemental Data [Abstract]
Increase (decrease) in level 3 assets	$ (1,400)