Commitments, Contingencies and Guarantees - Additional Information (Detail)		1 Months Ended	3 Months Ended
	Apr. 12, 2023 USD ($)	Jan. 31, 2022 USD ($) StateAttorneysGeneral Borrower	Mar. 31, 2023 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2023 USD ($)
Loss Contingencies [Line Items]
Accrued probable incurred loss					$ 73,000,000
Number of State Attorneys General under Agreement | StateAttorneysGeneral		40
Additional private loan provision for loan losses			$ 23,000,000
Aggregate cash fund contribution	$ 44,000,000
Net impact to operating expense			$ 0
Number of borrowers involved in cancellation of loan balance | Borrower		66,000
Aggregate outstanding balance of loans cancelled		$ 1,700,000,000
Expense on cancellation of loans		50,000,000
One-time payment		$ 145,000,000
Regulatory expenses				$ 205,000,000
Minimum [Member]
Loss Contingencies [Line Items]
Accrued probable incurred loss					0
Maximum [Member]
Loss Contingencies [Line Items]
Accrued probable incurred loss					250,000,000
SLM BankCo [Member] | Indemnification Matters [Member]
Loss Contingencies [Line Items]
Accrued liabilities related to indemnification matters					$ 0