Borrowings - Summary of Exposure Related To Unconsolidated VIEs (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024	Mar. 31, 2024	Dec. 31, 2023
Debt Instrument [Line Items]
Estimated Fair Value	$ 1,656,977	$ 1,933,226
Total Exposure	23,890	84,568	$ 32,034	$ 112,962
Variable Interest Entity, Not Primary Beneficiary | Private Education Loan term securitizations
Debt Instrument [Line Items]
Estimated Fair Value	549,949	571,795
Equity Interests	51,296	53,262
Total Exposure	$ 601,245	$ 625,057