Fair Value Measurements - Roll Forward of Financial Instruments Classified as Level 3 (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Liabilities
Unrealized gains (losses) recorded in OCI	$ 0	$ 0	$ 0	$ 0
Recurring | Level 3
Assets
Balance at Beginning of Period	504,000,000	394,000,000	539,000,000	327,000,000
Total Gains (Losses) Recorded in Earnings	(7,000,000)	43,000,000	(142,000,000)	76,000,000
Purchases / Closings	243,000,000	393,000,000	513,000,000	596,000,000
Sales	(96,000,000)	(10,000,000)	(96,000,000)	(46,000,000)
Settlement	0	0	0	0
Transfers Out	(186,000,000)	(352,000,000)	(356,000,000)	(485,000,000)
Balance at End of Period	458,000,000	468,000,000	458,000,000	468,000,000
Liabilities
Balance at Beginning of Period	(70,000,000)	(51,000,000)	(35,000,000)	(45,000,000)
Total Gains (Losses) Recorded in Earnings	0	(11,000,000)	(35,000,000)	(17,000,000)
Purchases / Closings	0	0	0	0
Sales	0	0	0	0
Settlement	70,000,000	0	70,000,000	0
Transfers Out	0	0	0	0
Balance at End of Period	0	(62,000,000)	0	(62,000,000)
Recurring | Level 3 | Home equity
Assets
Balance at Beginning of Period	2,000,000	2,000,000	2,000,000	2,000,000
Total Gains (Losses) Recorded in Earnings	0	0	0	0
Purchases / Closings	0	0	0	0
Sales	0	0	0	0
Settlement	0	0	0	0
Transfers Out	0	0	0	0
Balance at End of Period	2,000,000	2,000,000	2,000,000	2,000,000
Recurring | Level 3 | Mortgage servicing rights
Assets
Balance at Beginning of Period	428,000,000	223,000,000	329,000,000	291,000,000
Total Gains (Losses) Recorded in Earnings	(54,000,000)	(36,000,000)	(20,000,000)	(108,000,000)
Purchases / Closings	64,000,000	84,000,000	129,000,000	124,000,000
Sales	(96,000,000)	(10,000,000)	(96,000,000)	(46,000,000)
Settlement	0	0	0	0
Transfers Out	0	0	0	0
Balance at End of Period	342,000,000	261,000,000	342,000,000	261,000,000
Recurring | Level 3 | Rate lock commitments
Assets
Balance at Beginning of Period	74,000,000	169,000,000	208,000,000	34,000,000
Total Gains (Losses) Recorded in Earnings	47,000,000	79,000,000	(122,000,000)	184,000,000
Purchases / Closings	179,000,000	309,000,000	384,000,000	472,000,000
Sales	0	0	0	0
Settlement	0	0	0	0
Transfers Out	(186,000,000)	(352,000,000)	(356,000,000)	(485,000,000)
Balance at End of Period	114,000,000	205,000,000	114,000,000	205,000,000
Recurring | Level 3 | DOJ Liability
Liabilities
Balance at Beginning of Period	(70,000,000)	(35,000,000)	(35,000,000)	(35,000,000)
Total Gains (Losses) Recorded in Earnings	0	0	(35,000,000)	0
Purchases / Closings	0	0	0	0
Sales	0	0	0	0
Settlement	70,000,000	0	70,000,000	0
Transfers Out	0	0	0	0
Balance at End of Period	$ 0	(35,000,000)	$ 0	(35,000,000)
Recurring | Level 3 | Contingent consideration
Liabilities
Balance at Beginning of Period		(16,000,000)		(10,000,000)
Total Gains (Losses) Recorded in Earnings		(11,000,000)		(17,000,000)
Purchases / Closings		0		0
Sales		0		0
Settlement		0		0
Transfers Out		0		0
Balance at End of Period		$ (27,000,000)		$ (27,000,000)