Consolidated Balance Sheets - Supplemental Information (Unaudited) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023
Short-term borrowings	$ 5,326	$ 4,226
Long-term borrowings	47,545	53,402
FFELP Loans [Member]
Loans, net	32,940	37,925
Private Education Loans [Member]
Loans, net	16,238	16,902
Assets and Liabilities of Consolidated Variable Interest Entities [Member]
Loans, net	47,798	53,591
Restricted cash	2,904	1,937
Other assets, net	1,308	1,744
Short-term borrowings	4,225	3,634
Long-term borrowings	42,903	48,169
Net assets of consolidated variable interest entities	4,882	5,469
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | FFELP Loans [Member]
Loans, net	32,779	37,832
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Private Education Loans [Member]
Loans, net	$ 15,019	$ 15,759