Fair Value Measurements - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Equity securities without readily determinable fair value	$ 173,000,000	$ 171,000,000
Impairment on equity securities without readily determinable fair value	0
Loans, net of unearned income	101,854,000,000	101,185,000,000
Discontinued Operations | Education Lending
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	567,000,000	710,000,000
Loans carried at fair value	2,000,000	2,000,000
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	100,782,000,000	99,548,000,000
Loans carried at fair value	11,000,000	11,000,000
Carrying Amount | Discontinued Operations | Education Lending
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	567,000,000	674,000,000
Estimate of Fair Value Measurement
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	100,428,000,000	98,946,000,000
Loans carried at fair value	11,000,000	11,000,000
Estimate of Fair Value Measurement | Discontinued Operations | Education Lending
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans, net of unearned income	486,000,000	567,000,000
Fair Value, Recurring
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liabilities measured at fair value on non recurring basis	749,000,000	910,000,000
Loans, net of unearned income	11,000,000	11,000,000
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