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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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Borrowings - Summary of Exposure Related To Unconsolidated VIEs (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020	Jan. 01, 2020
Debt Instrument [Line Items]
Estimated Fair Value	$ 2,341,551	$ 2,517,956
Total Exposure	32,707	72,713	$ 19,367	$ 110,044	$ 115,758
Private Education Loan term securitizations \| Variable Interest Entity, Not Primary Beneficiary
Debt Instrument [Line Items]
Estimated Fair Value	230,372	192,245
Equity Interests	38,820	37,465
Total Exposure	$ 269,192	$ 229,710