Segment Reporting - Asset Information for Loans Segment (Detail) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021
Segment Reporting Information [Line Items]
Loans, net	$ 62,250	$ 72,812
Other	2,866	3,223
Total assets	70,795	80,605
Federal Education Loans [Member]
Segment Reporting Information [Line Items]
Loans, net	43,525	52,641
Cash and investments	2,746	2,071
Other	2,229	2,183
Total assets	48,500	56,895
Consumer Lending [Member]
Segment Reporting Information [Line Items]
Loans, net	18,725	20,171
Cash and investments	617	824
Other	453	815
Total assets	$ 19,795	$ 21,810