v3.26.1
Segment Reporting - Segment Results and Reconciliations to GAAP - Reportable Segment Significant Operating Expenses (Details) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Segment Reporting [Line Items]        
Servicing expenses $ 28 $ 32 $ 58 $ 67
Information technology expenses 16 28 36 59
Corporate expenses 18 20 40 45
Other/remaining expenses 20 20 37 56
Total operating expenses 82 100 171 227
Consumer Lending Segment [Member]        
Segment Reporting [Line Items]        
Servicing expenses 14 14 28 28
Information technology expenses 10 8 20 17
Corporate expenses 0 1 1 1
Other/remaining expenses 18 13 32 24
Total operating expenses 42 36 81 70
Federal Education Loans [Member]        
Segment Reporting [Line Items]        
Servicing expenses 14 16 30 34
Information technology expenses 0 0 0 0
Corporate expenses 0 0 0 1
Other/remaining expenses 1 1 1 2
Total operating expenses 15 17 31 37
Business Processing [Member]        
Segment Reporting [Line Items]        
Servicing expenses 0 0 0 0
Information technology expenses 0 0 0 1
Corporate expenses 0 0 0 0
Other/remaining expenses 0 0 0 19
Total operating expenses 0 0 0 20
Other Segment [Member]        
Segment Reporting [Line Items]        
Servicing expenses 0 2 0 5
Information technology expenses 6 20 16 41
Corporate expenses 18 19 39 43
Other/remaining expenses 1 6 4 11
Total operating expenses $ 25 $ 47 $ 59 $ 100