v3.26.1
Segment Reporting - Segment Results and Reconciliations to GAAP (Detail) - USD ($)
$ in Millions
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Interest income:        
Cash and investments $ 18 $ 22 $ 35 $ 43
Total interest income 682 778 1,376 1,580
Total interest expense 560 650 1,123 1,322
Net interest income (loss) 122 128 253 258
Less: provisions for loan losses 26 37 54 67
Net interest income (loss) after provisions for loan losses 96 91 199 191
Other income (loss):        
Servicing revenue 10 14 21 27
Asset recovery and business processing revenue 0 0 0 23
Other revenue (loss) 18 14 28 3
Total other income (loss) 28 28 49 53
Expenses:        
Direct operating expenses 57 53 112 127
Unallocated shared services expenses 25 47 59 100
Total operating expenses 82 100 171 227
Goodwill and acquired intangible asset impairment and amortization 0 1 4 2
Restructuring/other reorganization expenses 3 0 2 3
Total expenses 85 101 177 232
Income before income tax expense 39 18 71 12
Income tax expense (benefit) 14 4 29 1
Net income 25 14 42 11
Federal Education Loans [Member]        
Expenses:        
Total operating expenses 15 17 31 37
Business Processing [Member]        
Expenses:        
Total operating expenses 0 0 0 20
Other Segment [Member]        
Expenses:        
Total operating expenses 25 47 59 100
Operating Segments [Member]        
Interest income:        
Net interest income (loss) 120 131 246 275
Less: provisions for loan losses 26 37 54 67
Other income (loss):        
Total other income (loss) 27 33 43 83
Expenses:        
Total operating expenses 82 100 171 227
Goodwill and acquired intangible asset impairment and amortization 0 0 0 0
Restructuring/other reorganization expenses 3 0 2 3
Total expenses 85 100 173 230
Income before income tax expense 36 27 62 61
Income tax expense (benefit) 9 6 15 14
Net income 27 21 47 47
Operating Segments [Member] | Federal Education Loans [Member]        
Interest income:        
Cash and investments 8 10 17 20
Total interest income 399 493 808 995
Total interest expense 351 438 714 892
Net interest income (loss) 48 55 94 103
Less: provisions for loan losses 8 8 17 16
Net interest income (loss) after provisions for loan losses 40 47 77 87
Other income (loss):        
Servicing revenue 8 11 17 21
Asset recovery and business processing revenue 0 0 0 0
Other revenue (loss) 0 (1) 0 (1)
Total other income (loss) 8 10 17 20
Expenses:        
Direct operating expenses 15 17 31 37
Unallocated shared services expenses 0 0 0 0
Total operating expenses 15 17 31 37
Goodwill and acquired intangible asset impairment and amortization 0 0 0 0
Restructuring/other reorganization expenses 0 0 0 0
Total expenses 15 17 31 37
Income before income tax expense 33 40 63 70
Income tax expense (benefit) 7 10 15 16
Net income 26 30 48 54
Operating Segments [Member] | Consumer Lending [Member]        
Interest income:        
Cash and investments 5 5 9 10
Total interest income 278 278 559 572
Total interest expense 185 183 365 364
Net interest income (loss) 93 95 194 208
Less: provisions for loan losses 18 29 37 51
Net interest income (loss) after provisions for loan losses 75 66 157 157
Other income (loss):        
Servicing revenue 2 3 4 6
Asset recovery and business processing revenue 0 0 0 0
Other revenue (loss) 0 0 0 0
Total other income (loss) 2 3 4 6
Expenses:        
Direct operating expenses 42 36 81 70
Unallocated shared services expenses 0 0 0 0
Total operating expenses 42 36 81 70
Goodwill and acquired intangible asset impairment and amortization 0 0 0 0
Restructuring/other reorganization expenses 0 0 0 0
Total expenses 42 36 81 70
Income before income tax expense 35 33 80 93
Income tax expense (benefit) 8 7 18 21
Net income 27 26 62 72
Operating Segments [Member] | Business Processing [Member]        
Interest income:        
Cash and investments 0 0 0 0
Total interest income 0 0 0 0
Total interest expense 0 0 0 0
Net interest income (loss) 0 0 0 0
Less: provisions for loan losses 0 0 0 0
Net interest income (loss) after provisions for loan losses 0 0 0 0
Other income (loss):        
Servicing revenue 0 0 0 0
Asset recovery and business processing revenue 0 0 0 23
Other revenue (loss) 0 0 0 0
Total other income (loss) 0 0 0 23
Expenses:        
Direct operating expenses 0 0 0 20
Unallocated shared services expenses 0 0 0 0
Total operating expenses 0 0 0 20
Goodwill and acquired intangible asset impairment and amortization 0 0 0 0
Restructuring/other reorganization expenses 0 0 0 0
Total expenses 0 0 0 20
Income before income tax expense 0 0 0 3
Income tax expense (benefit) 0 0 0 1
Net income 0 0 0 2
Operating Segments [Member] | Other Segment [Member]        
Interest income:        
Cash and investments 5 7 9 13
Total interest income 5 7 9 13
Total interest expense 26 26 51 49
Net interest income (loss) (21) (19) (42) (36)
Less: provisions for loan losses 0 0 0 0
Net interest income (loss) after provisions for loan losses (21) (19) (42) (36)
Other income (loss):        
Servicing revenue 0 0 0 0
Asset recovery and business processing revenue 0 0 0 0
Other revenue (loss) 17 20 22 34
Total other income (loss) 17 20 22 34
Expenses:        
Direct operating expenses 0 0 0 0
Unallocated shared services expenses 25 47 59 100
Total operating expenses 25 47 59 100
Goodwill and acquired intangible asset impairment and amortization 0 0 0 0
Restructuring/other reorganization expenses 3 0 2 3
Total expenses 28 47 61 103
Income before income tax expense (32) (46) (81) (105)
Income tax expense (benefit) (6) (11) (18) (24)
Net income (26) (35) (63) (81)
Adjustments [Member] | Reclassifications [Member]        
Interest income:        
Net interest income (loss) 1 5 3 11
Other income (loss):        
Total other income (loss) (1) (5) (3) (11)
Expenses:        
Total operating expenses 0 0 0 0
Goodwill and acquired intangible asset impairment and amortization 0 0 0 0
Restructuring/other reorganization expenses 0 0 0 0
Total expenses 0 0 0 0
Income before income tax expense 0 0 0 0
Income tax expense (benefit) 0 0 0 0
Net income 0 0 0 0
Adjustments [Member] | Additions (Subtractions) [Member]        
Interest income:        
Net interest income (loss) (3) (2) (10) 6
Other income (loss):        
Total other income (loss) 0 10 (3) 41
Expenses:        
Total operating expenses 0 0 0 0
Goodwill and acquired intangible asset impairment and amortization 0 (1) (4) (2)
Restructuring/other reorganization expenses 0 0 0 0
Total expenses 0 (1) (4) (2)
Income before income tax expense (3) 9 (9) 49
Income tax expense (benefit) (5) 2 (14) 13
Net income 2 7 5 36
Adjustments [Member] | Total Adjustments [Member]        
Interest income:        
Net interest income (loss) (2) 3 (7) 17
Net interest income (loss) after provisions for loan losses (2) 3 (7) 17
Other income (loss):        
Total other income (loss) (1) 5 (6) 30
Expenses:        
Total operating expenses 0 0 0 0
Goodwill and acquired intangible asset impairment and amortization 0 (1) (4) (2)
Restructuring/other reorganization expenses 0 0 0 0
Total expenses 0 (1) (4) (2)
Income before income tax expense (3) 9 (9) 49
Income tax expense (benefit) (5) 2 (14) 13
Net income 2 7 5 36
Education Loan Portfolio [Member]        
Interest income:        
Total interest income 664 756 1,341 1,537
Education Loan Portfolio [Member] | Operating Segments [Member] | Federal Education Loans [Member]        
Interest income:        
Total interest income 391 483 791 975
Education Loan Portfolio [Member] | Operating Segments [Member] | Consumer Lending [Member]        
Interest income:        
Total interest income 273 273 550 562
Education Loan Portfolio [Member] | Operating Segments [Member] | Business Processing [Member]        
Interest income:        
Total interest income 0 0 0 0
Education Loan Portfolio [Member] | Operating Segments [Member] | Other Segment [Member]        
Interest income:        
Total interest income $ 0 $ 0 $ 0 $ 0