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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	Sep. 30, 2022	Jun. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Jun. 30, 2021	Dec. 31, 2020	Jan. 01, 2020
Debt Instrument [Line Items]
Estimated Fair Value	$ 2,427,540		$ 2,517,956
Total Exposure	107,794	$ 113,525	72,713	$ 99,131	$ 64,772	$ 110,044	$ 115,758
Private Education Loan term securitizations \| Variable Interest Entity, Not Primary Beneficiary
Debt Instrument [Line Items]
Estimated Fair Value	296,516		192,245
Equity Interests	47,386		37,465
Total Exposure	$ 343,902		$ 229,710