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Segment Reporting - Segment Results and Reconciliations to GAAP (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015
Interest income: |  |  |  |
Education loans | $ 1,032 | $ 1,074 | $ 3,096 | $ 3,227
Other loans | 2 | 1 | 5 | 5
Cash and investments | 5 | 2 | 17 | 6
Total interest income | 1,039 | 1,077 | 3,118 | 3,238
Total interest expense | 627 | 524 | 1,791 | 1,553
Net interest income (loss) | 412 | 553 | 1,327 | 1,685
Less: provisions for loan losses | 106 | 123 | 327 | 446
Net interest income (loss) after provisions for loan losses | 306 | 430 | 1,000 | 1,239
Other income (loss): |  |  |  |
Servicing revenue | 76 | 76 | 230 | 258
Asset recovery and business processing revenue | 97 | 85 | 288 | 273
Other income (loss) | 137 | 20 | 75 | 88
Gains on sales of loans and investments |  |  |  | 12
Gains on debt repurchases | 1 |  | 1 |
Total other income | 311 | 181 | 594 | 631
Expenses: |  |  |  |
Direct operating expenses | 177 | 174 | 538 | 514
Overhead expenses | 51 | 54 | 168 | 169
Total operating expenses | 228 | 228 | 706 | 683
Goodwill and acquired intangible asset impairment and amortization | 12 | 3 | 22 | 7
Restructuring and other reorganization expenses |  |  |  | 32
Total expenses | 240 | 231 | 728 | 722
Income (loss) from continuing operations, before income tax expense (benefit) | 377 | 380 | 866 | 1,148
Income tax expense (benefit) | 147 | 144 | 331 | 438
Net income (loss) from continuing operations | 230 | 236 | 535 | 710
Income (loss) from discontinued operations, net of tax expense (benefit) |  | 1 |  | 1
Net income (loss) | 230 | 237 | 535 | 711
Reclassifications [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 28 | 164 | 222 | 489
Total interest income | 28 | 164 | 222 | 489
Total interest expense | 7 | 11 | 25 | 27
Net interest income (loss) | 21 | 153 | 197 | 462
Net interest income (loss) after provisions for loan losses | 21 | 153 | 197 | 462
Other income (loss): |  |  |  |
Other income (loss) | (21) | (153) | (197) | (462)
Total other income | (21) | (153) | (197) | (462)
Additions/ (Subtractions) [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | (14) | (60) | (99) | (178)
Total interest income | (14) | (60) | (99) | (178)
Net interest income (loss) | (14) | (60) | (99) | (178)
Net interest income (loss) after provisions for loan losses | (14) | (60) | (99) | (178)
Other income (loss): |  |  |  |
Other income (loss) | 153 | 168 | 260 | 535
Total other income | 153 | 168 | 260 | 535
Expenses: |  |  |  |
Goodwill and acquired intangible asset impairment and amortization | 12 | 3 | 22 | 7
Restructuring and other reorganization expenses |  |  |  | 32
Total expenses | 12 | 3 | 22 | 39
Income (loss) from continuing operations, before income tax expense (benefit) | 127 | 105 | 139 | 318
Income tax expense (benefit) | 54 | 42 | 62 | 130
Net income (loss) from continuing operations | 73 | 63 | 77 | 188
Net income (loss) | 73 | 63 | 77 | 188
Total Adjustments [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 14 | 104 | 123 | 311
Total interest income | 14 | 104 | 123 | 311
Total interest expense | 7 | 11 | 25 | 27
Net interest income (loss) | 7 | 93 | 98 | 284
Net interest income (loss) after provisions for loan losses | 7 | 93 | 98 | 284
Other income (loss): |  |  |  |
Other income (loss) | 132 | 15 | 63 | 73
Total other income | 132 | 15 | 63 | 73
Expenses: |  |  |  |
Total operating expenses | 0 | 0 | 0 | 0
Goodwill and acquired intangible asset impairment and amortization | 12 | 3 | 22 | 7
Restructuring and other reorganization expenses |  |  |  | 32
Total expenses | 12 | 3 | 22 | 39
Income (loss) from continuing operations, before income tax expense (benefit) | 127 | 105 | 139 | 318
Income tax expense (benefit) | 54 | 42 | 62 | 130
Net income (loss) from continuing operations | 73 | 63 | 77 | 188
Net income (loss) | 73 | 63 | 77 | 188
Operating Segments [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 1,018 | 970 | 2,973 | 2,916
Other loans | 2 | 1 | 5 | 5
Cash and investments | 5 | 2 | 17 | 6
Total interest income | 1,025 | 973 | 2,995 | 2,927
Total interest expense | 620 | 513 | 1,766 | 1,526
Net interest income (loss) | 405 | 460 | 1,229 | 1,401
Less: provisions for loan losses | 106 | 123 | 327 | 446
Net interest income (loss) after provisions for loan losses | 299 | 337 | 902 | 955
Other income (loss): |  |  |  |
Servicing revenue | 76 | 76 | 230 | 258
Asset recovery and business processing revenue | 97 | 85 | 288 | 273
Other income (loss) | 5 | 5 | 12 | 15
Gains on sales of loans and investments |  |  |  | 12
Gains on debt repurchases | 1 |  | 1 |
Total other income | 179 | 166 | 531 | 558
Expenses: |  |  |  |
Direct operating expenses | 177 | 174 | 538 | 514
Overhead expenses | 51 | 54 | 168 | 169
Total operating expenses | 228 | 228 | 706 | 683
Total expenses | 228 | 228 | 706 | 683
Income (loss) from continuing operations, before income tax expense (benefit) | 250 | 275 | 727 | 830
Income tax expense (benefit) | 93 | 102 | 269 | 308
Net income (loss) from continuing operations | 157 | 173 | 458 | 522
Income (loss) from discontinued operations, net of tax expense (benefit) |  | 1 |  | 1
Net income (loss) | 157 | 174 | 458 | 523
Operating Segments [Member] | FFELP Loans Segment [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 617 | 526 | 1,760 | 1,581
Cash and investments | 4 | 2 | 12 | 5
Total interest income | 621 | 528 | 1,772 | 1,586
Total interest expense | 413 | 317 | 1,159 | 928
Net interest income (loss) | 208 | 211 | 613 | 658
Less: provisions for loan losses | 13 | 7 | 30 | 19
Net interest income (loss) after provisions for loan losses | 195 | 204 | 583 | 639
Other income (loss): |  |  |  |
Servicing revenue | 13 | 16 | 45 | 78
Gains on sales of loans and investments |  |  |  | 12
Total other income | 13 | 16 | 45 | 90
Expenses: |  |  |  |
Direct operating expenses | 99 | 109 | 305 | 336
Total operating expenses | 99 | 109 | 305 | 336
Total expenses | 99 | 109 | 305 | 336
Income (loss) from continuing operations, before income tax expense (benefit) | 109 | 111 | 323 | 393
Income tax expense (benefit) | 40 | 41 | 120 | 146
Net income (loss) from continuing operations | 69 | 70 | 203 | 247
Net income (loss) | 69 | 70 | 203 | 247
Operating Segments [Member] | Private Education Loans Segment [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 401 | 444 | 1,213 | 1,335
Cash and investments |  |  | 2 |
Total interest income | 401 | 444 | 1,215 | 1,335
Total interest expense | 178 | 170 | 522 | 514
Net interest income (loss) | 223 | 274 | 693 | 821
Less: provisions for loan losses | 92 | 117 | 296 | 428
Net interest income (loss) after provisions for loan losses | 131 | 157 | 397 | 393
Other income (loss): |  |  |  |
Servicing revenue | 4 | 5 | 11 | 17
Total other income | 4 | 5 | 11 | 17
Expenses: |  |  |  |
Direct operating expenses | 40 | 39 | 124 | 127
Total operating expenses | 40 | 39 | 124 | 127
Total expenses | 40 | 39 | 124 | 127
Income (loss) from continuing operations, before income tax expense (benefit) | 95 | 123 | 284 | 283
Income tax expense (benefit) | 35 | 46 | 105 | 105
Net income (loss) from continuing operations | 60 | 77 | 179 | 178
Net income (loss) | 60 | 77 | 179 | 178
Operating Segments [Member] | Business Services Segment [Member] |  |  |  |
Other income (loss): |  |  |  |
Servicing revenue | 155 | 161 | 470 | 487
Asset recovery and business processing revenue | 97 | 85 | 288 | 273
Other income (loss) |  | 2 | 2 | 4
Total other income | 252 | 248 | 760 | 764
Expenses: |  |  |  |
Direct operating expenses | 124 | 123 | 383 | 355
Total operating expenses | 124 | 123 | 383 | 355
Total expenses | 124 | 123 | 383 | 355
Income (loss) from continuing operations, before income tax expense (benefit) | 128 | 125 | 377 | 409
Income tax expense (benefit) | 47 | 46 | 140 | 152
Net income (loss) from continuing operations | 81 | 79 | 237 | 257
Net income (loss) | 81 | 79 | 237 | 257
Operating Segments [Member] | Other Segment [Member] |  |  |  |
Interest income: |  |  |  |
Other loans | 2 | 1 | 5 | 5
Cash and investments | 1 |  | 3 | 1
Total interest income | 3 | 1 | 8 | 6
Total interest expense | 29 | 26 | 85 | 84
Net interest income (loss) | (26) | (25) | (77) | (78)
Less: provisions for loan losses | 1 | (1) | 1 | (1)
Net interest income (loss) after provisions for loan losses | (27) | (24) | (78) | (77)
Other income (loss): |  |  |  |
Other income (loss) | 5 | 3 | 10 | 11
Gains on debt repurchases | 1 |  | 1 |
Total other income | 6 | 3 | 11 | 11
Expenses: |  |  |  |
Direct operating expenses | 10 | 9 | 22 | 20
Overhead expenses | 51 | 54 | 168 | 169
Total operating expenses | 61 | 63 | 190 | 189
Total expenses | 61 | 63 | 190 | 189
Income (loss) from continuing operations, before income tax expense (benefit) | (82) | (84) | (257) | (255)
Income tax expense (benefit) | (29) | (31) | (96) | (95)
Net income (loss) from continuing operations | (53) | (53) | (161) | (160)
Income (loss) from discontinued operations, net of tax expense (benefit) |  | 1 |  | 1
Net income (loss) | (53) | (52) | (161) | (159)
Eliminations [Member] |  |  |  |
Other income (loss): |  |  |  |
Servicing revenue | (96) | (106) | (296) | (324)
Total other income | (96) | (106) | (296) | (324)
Expenses: |  |  |  |
Direct operating expenses | (96) | (106) | (296) | (324)
Total operating expenses | (96) | (106) | (296) | (324)
Total expenses | $ (96) | $ (106) | $ (296) | $ (324)

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