Accounting Policies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change	$ 5,240	$ 6,340	$ 5,240	$ 6,340	$ 5,601	$ 6,789	$ 6,126	$ 6,269
Assets of managed investment entities	29,942		29,942			73,710
Liabilities of managed investment entities	24,702		24,702			66,921
Operating lease liability	$ 136		$ 136			$ 159
Operating lease liability, current, Statement of Financial Position	Other liabilities		Other liabilities			Other liabilities
Operating lease right-of-use asset	$ 118		$ 118			$ 139
Weighted average common shares adjustment related to stock-based compensation (shares)	400,000	300,000	600,000	500,000
Anti-dilutive potential common shares related to stock-based compensation plans (shares)	0	0	0	0
Maturities of short term investments			3 months
New collateralized loan obligation temporary warehousing entities
Significant Accounting Policies [Line Items]
Assets of managed investment entities	$ 171		$ 171
Liabilities of managed investment entities	131		131
Retained Earnings
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change	$ 3,680	$ 3,737	$ 3,680	$ 3,737	$ 4,023	$ 4,149	$ 3,685	4,009
Cumulative effect adjustment in period of adoption | Retained Earnings
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change								7
Cumulative effect adjustment in period of adoption | Retained Earnings | Accounting Standards Update 2016-13
Significant Accounting Policies [Line Items]
Cumulative effect of accounting change								$ 7