Income Taxes - Schedule of Deferred Tax Assets and Liabilities (Detail) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Deferred tax assets:
Loan reserves	$ 237	$ 297
Accrued expenses not currently deductible	39	33
Education loan premiums and discounts, net	32	41
Operating loss and credit carryovers	11	12
Stock-based compensation plans	5	5
Other	18	19
Total deferred tax assets	342	407
Deferred tax liabilities:
Market value adjustments on education loans, investments and derivatives	114	201
Acquired intangible assets	23	22
Original issue discount on borrowings	13	13
Other	7	11
Total deferred tax liabilities	157	247
Net deferred tax assets	$ 185	$ 160