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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	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Debt Instrument [Line Items]
Estimated Fair Value	$ 2,072,309		$ 1,996,634
Total Exposure	64,772	$ 19,367	110,044	$ 85,958	$ 29,707	$ 2,481
Private Education Loan securitization \| Variable Interest Entity, Not Primary Beneficiary
Debt Instrument [Line Items]
Estimated Fair Value	218,047		68,908
Equity Interests	35,908		16,923
Total Exposure	$ 253,955		$ 85,831