Consolidated Balance Sheets - Supplemental Information (Unaudited) - USD ($) $ in Millions	Jun. 30, 2025	Dec. 31, 2024
Short-term borrowings	$ 4,752	$ 5,134
Long-term borrowings	42,345	43,184
FFELP Loans [Member]
Loans, net	29,618	30,852
Private Education Loans [Member]
Loans, net	15,530	15,716
Assets and Liabilities of Consolidated Variable Interest Entities [Member]
Loans, net	43,786	45,258
Restricted cash	1,363	1,364
Other assets, net	1,366	1,224
Short-term borrowings	4,153	4,532
Long-term borrowings	37,552	38,497
Net assets of consolidated variable interest entities	4,810	4,817
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | FFELP Loans [Member]
Loans, net	29,565	30,620
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Private Education Loans [Member]
Loans, net	$ 14,221	$ 14,638