Contingent Liabilities and Guarantees - Additional Information (Details) $ in Millions	6 Months Ended
Jun. 30, 2021 USD ($)
Written put options
Commitments Contingencies And Guarantees [Line Items]
Weighted average life of written put options	2 years 2 months 12 days
Standby letters of credit
Commitments Contingencies And Guarantees [Line Items]
Remaining weighted-average life of standby letters of credit in years	1 year 9 months 18 days
Recourse agreement with FNMA
Commitments Contingencies And Guarantees [Line Items]
Weighted-average remaining term for outstanding commercial mortgage loans in years	7 years 8 months 12 days
Unpaid principal balance outstanding of loans sold	$ 19,800
Maximum potential amount of undiscounted future payments possibly required as percentage of principal balance of loans outstanding	30.00%
Residential mortgage reserve
Commitments Contingencies And Guarantees [Line Items]
Unpaid principal balance outstanding of loans sold	$ 9,400
Maximum potential amount of undiscounted future payments possibly required as percentage of principal balance of loans outstanding	30.00%
Liability for estimated repurchase obligations on loans sold	$ 12
Minimum \| Standby letters of credit
Commitments Contingencies And Guarantees [Line Items]
Remaining actual life of standby letters of credit	1 year
Minimum \| Low
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	0.00%
Minimum \| Moderate
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	30.00%
Minimum \| High
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	70.00%
Maximum \| Standby letters of credit
Commitments Contingencies And Guarantees [Line Items]
Remaining actual life of standby letters of credit	13 years 4 months 24 days
Maximum \| Low
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	30.00%
Maximum \| Moderate
Commitments Contingencies And Guarantees [Line Items]
Guarantee obligations, percentage	70.00%

Commitments Contingencies And Guarantees [Line Items]

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- Definition

Guarantor Obligations, Maximum Exposure, Undiscounted as Percentage of Total Loans Outstanding

+ References

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- Definition

Remaining actual life letters of credit.

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- Definition

Remaining weighted-average life of standby letters of credit.

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- Definition

Weighted average life of written put options.

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- Definition

Weighted-average remaining term for outstanding commercial mortgage loans.

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- Definition

Amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(ii)(A)(ii))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
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-Paragraph 1
-Subparagraph (SX 210.4-08(m)(1)(i))
-URI http://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

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- Definition

Indicates, if estimable, (as a percentage) the approximate extent to which the proceeds from liquidation of any assets held either as collateral or by third parties would be expected to cover the maximum potential amount of future payments under the guarantee or each group of similar guarantees.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 460
-SubTopic 10
-Section 50
-Paragraph 4
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Amount of the recorded obligation to transfer funds in the future for fixed or minimum amounts or quantities of goods or services at fixed or minimum prices (for example, as in take-or-pay contracts or throughput contracts).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 440
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=123406679&loc=d3e25383-109308

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