Commitments, Contingencies and Guarantees - Additional Information (Detail)	1 Months Ended	3 Months Ended
	Jan. 31, 2022 USD ($) StateAttorneysGeneral Borrower	Dec. 31, 2021 USD ($)	Dec. 31, 2022 USD ($)
Loss Contingencies [Line Items]
Number of State Attorneys General under Agreement | StateAttorneysGeneral	40
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
SLM BankCo [Member] | Indemnification Matters [Member]
Loss Contingencies [Line Items]
Reserve for estimated amounts and costs incurred			$ 0