Fair Value Measurements - Roll Forward of Financial Instruments Classified as Level 3 (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Liabilities
Unrealized gains (losses) recorded in OCI	$ 0	$ 0	$ 0	$ 0
Recurring \| Level 3
Assets
Balance at Beginning of Period	458	468	539	327
Total Gains (Losses) Recorded in Earnings	31	67	(111)	143
Purchases / Closings	202	418	715	1,014
Sales	(62)	0	(158)	(46)
Settlement	(1)	0	(1)	0
Transfers Out	(202)	(371)	(558)	(856)
Balance at End of Period	426	582	426	582
Liabilities
Balance at Beginning of Period		(62)		(45)
Total Gains (Losses) Recorded in Earnings		0		(17)
Purchases / Closings		0		0
Sales		0		0
Settlement		27		27
Transfers Out		0		0
Balance at End of Period		(35)		(35)
Recurring \| Level 3 \| Home equity
Assets
Balance at Beginning of Period	2	2	2	2
Total Gains (Losses) Recorded in Earnings	0	0	0	0
Purchases / Closings	0	0	0	0
Sales	0	0	0	0
Settlement	(1)	0	(1)	0
Transfers Out	0	0	0	0
Balance at End of Period	1	2	1	2
Recurring \| Level 3 \| Mortgage servicing rights
Assets
Balance at Beginning of Period	342	261	329	291
Total Gains (Losses) Recorded in Earnings	(7)	(23)	(27)	(131)
Purchases / Closings	67	85	196	209
Sales	(62)	0	(158)	(46)
Settlement	0	0	0	0
Transfers Out	0	0	0	0
Balance at End of Period	340	323	340	323
Recurring \| Level 3 \| Rate lock commitments
Assets
Balance at Beginning of Period	114	205	208	34
Total Gains (Losses) Recorded in Earnings	38	90	(84)	274
Purchases / Closings	135	333	519	805
Sales	0	0	0	0
Settlement	0	0	0	0
Transfers Out	(202)	(371)	(558)	(856)
Balance at End of Period	85	257	85	257
Recurring \| Level 3 \| DOJ Liability
Liabilities
Balance at Beginning of Period		(35)	(35)	(35)
Total Gains (Losses) Recorded in Earnings		0	(35)	0
Purchases / Closings		0	0	0
Sales		0	0	0
Settlement		0	70	0
Transfers Out		0	0	0
Balance at End of Period	$ 0	(35)	$ 0	(35)
Recurring \| Level 3 \| Contingent consideration
Liabilities
Balance at Beginning of Period		(27)		(10)
Total Gains (Losses) Recorded in Earnings		0		(17)
Purchases / Closings		0		0
Sales		0		0
Settlement		27		27
Transfers Out		0		0
Balance at End of Period		$ 0		$ 0

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=117815213&loc=d3e19207-110258

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- Definition

Amount of gain (loss) recognized in other comprehensive income (OCI) from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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Amount of sale of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of transfer of financial instrument classified as an asset into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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- Definition

Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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Amount of purchases of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Amount of transfers of financial instrument classified as a liability into (out of) level 3 of the fair value hierarchy.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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