Consolidated Balance Sheets - Supplemental Information (Unaudited) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Short-term borrowings	$ 5,753	$ 5,870
Long-term borrowings	57,388	61,026
FFELP Loans [Member]
Loans, net	42,148	43,525
Private Education Loans [Member]
Loans, net	18,275	18,725
Assets and Liabilities of Consolidated Variable Interest Entities [Member]
Loans, net	58,908	60,672
Restricted cash	2,180	3,233
Other assets, net	1,534	1,356
Short-term borrowings	4,520	4,458
Long-term borrowings	52,714	55,598
Net assets of consolidated variable interest entities	5,388	5,205
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | FFELP Loans [Member]
Loans, net	42,086	43,465
Assets and Liabilities of Consolidated Variable Interest Entities [Member] | Private Education Loans [Member]
Loans, net	$ 16,822	$ 17,207