Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
Dec. 31, 2023	Dec. 31, 2022
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities without readily determinable fair value	$ 339,000,000	$ 249,000,000
Impairment on equity securities without readily determinable fair value	0
Loans, net of unearned income	112,606,000,000	119,394,000,000
Discontinued operations \| Education Lending
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	339,000,000	434,000,000
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	111,089,000,000	118,048,000,000
Carrying Amount \| Discontinued operations \| Education Lending
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	339,000,000	434,000,000
Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	105,950,000,000	112,590,000,000
Estimate of Fair Value Measurement \| Discontinued operations \| Education Lending
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	264,000,000	357,000,000
Fair Value, Nonrecurring \| Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities measured at fair value on non recurring basis	$ 0	$ 0

Amount of investment in equity security without readily determinable fair value.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-3

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- Definition

Amount of impairment loss on investment in equity security without readily determinable fair value.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-3

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- Definition

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+ References

No definition available.

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- Definition

Amortized cost excluding accrued interest, before allowance for credit loss, of financing receivable. Excludes net investment in lease.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479344/326-20-45-1

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 3B
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-3B

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 5
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479319/326-20-50-5

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- Definition

Fair value of financial and nonfinancial obligations.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147482106/820-10-50-2

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