Financial Instruments Subject to Off-Balance Sheet Credit Risk (Offsetting Assets and Liabilities) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Resale agreements
Gross Assets	$ 13,096	$ 14,904
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Presented in the Condensed Consolidated Balance Sheets	13,096	14,904
Counterparty Offsetting	0	0
Collateral	(13,096)	(14,904)
Net Amount	0	0
Securities borrowed
Gross Assets	582	873
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Presented in the Condensed Consolidated Balance Sheets	582	873
Counterparty Offsetting	(383)	(673)
Collateral	(195)	(195)
Net Amount	4	5
Total Gross Assets	13,678	15,777
Total Assets, Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Total Assets, Net Amounts Presented in the Condensed Consolidated Balance Sheets	13,678	15,777
Total Assets, Gross Amounts Not Offset in the Consolidated Balance Sheet, Counterparty Offsetting	(383)	(673)
Total Assets, Gross Amounts Not Offset in the Consolidated Balance Sheet, Collateral	(13,291)	(15,099)
Total Assets, Net Amount	4	5
Securities loaned
Gross Liabilities	7,158	7,549
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Net Amounts Presented in the Condensed Consolidated Balance Sheets	7,158	7,549
Counterparty Offsetting	(383)	(673)
Collateral	(6,015)	(6,049)
Net Amount	760	827
Secured short-term borrowings
Gross Liabilities	1,850
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0
Net Amounts Presented in the Condensed Consolidated Balance Sheets	1,850
Counterparty Offsetting	0
Collateral	(1,850)
Net Amount	0
Total Gross Liabilities	9,008	7,549
Gross Amounts Offset in the Condensed Consolidated Balance Sheets	0	0
Total Liabilities, Net Amounts Presented in the Consolidated Balance Sheet	9,008	7,549
Total Liabilities, Gross Amounts Not Offset in the Consolidated Balance Sheet, Counterparty Offsetting	(383)	(673)
Total Liabilities, Gross Amounts Not Offset in the Consolidated Balance Sheet, Collateral	(7,865)	(6,049)
Total Liabilities, Net Amount	760	827
Offsetting Assets [Line Items]
Fair value of client securities available to be pledged	120,306	84,006
Resale And Repurchase Agreements [Member]
Offsetting Assets [Line Items]
Fair value of client securities available to be pledged	$ 13,400	$ 15,200