Fair Value Measurement - Nonrecurring Basis (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Equity securities adjusted based on the measurement alternative	$ 2,798	$ 2,620	$ 2,798	$ 2,620	$ 2,400
Net gains as a result of measurement alternative	109	4	116	13
Net losses as a result of measurement alternative	(7)	(9)	$ (9)	(171)
Residential mortgage | Broker price opinions | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value inputs, liquidation value discount			12.00%
Residential mortgage | Broker price opinions | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value inputs, liquidation value discount			45.00%
Residential mortgage | Broker price opinions | Weighted average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value inputs, liquidation value discount			26.00%
Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	3,219	3,012	$ 3,219	3,012
Total liabilities measured at fair value on a nonrecurring basis	5	95	5	95
Total nonrecurring fair value gains/(losses)	88	387	67	(604)
Nonrecurring | Accounts payable and other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value on a nonrecurring basis	5	95	5	95
Total nonrecurring fair value gains/(losses)	7	465	6	(95)
Nonrecurring | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	2,377	2,616	2,377	2,616
Total nonrecurring fair value gains/(losses)	(11)	(39)	(32)	(303)
Nonrecurring | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	842	396	842	396
Total nonrecurring fair value gains/(losses)	92	(39)	93	(206)
Net gains as a result of measurement alternative	102		107
Net losses as a result of measurement alternative		(4)		(158)
Nonrecurring | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	0	0	0	0
Total liabilities measured at fair value on a nonrecurring basis	0	0	0	0
Nonrecurring | Level 1 | Accounts payable and other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value on a nonrecurring basis	0	0	0	0
Nonrecurring | Level 1 | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	0	0	0	0
Nonrecurring | Level 1 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	0	0	0	0
Nonrecurring | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	2,059	1,797	2,059	1,797
Total liabilities measured at fair value on a nonrecurring basis	0	0	0	0
Nonrecurring | Level 2 | Accounts payable and other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value on a nonrecurring basis	0	0	0	0
Nonrecurring | Level 2 | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	2,048	1,793	2,048	1,793
Nonrecurring | Level 2 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	11	4	11	4
Nonrecurring | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	1,160	1,215	1,160	1,215
Total liabilities measured at fair value on a nonrecurring basis	5	95	5	95
Nonrecurring | Level 3 | Accounts payable and other liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total liabilities measured at fair value on a nonrecurring basis	5	95	5	95
Nonrecurring | Level 3 | Loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	329	823	329	823
Nonrecurring | Level 3 | Residential mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	179		179
Nonrecurring | Level 3 | Other assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total assets measured at fair value on a nonrecurring basis	831	$ 392	831	$ 392
Equity securities adjusted based on the measurement alternative	$ 754		$ 754