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Segment Reporting - Segment Results and Reconciliations to GAAP (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2016 | Jun. 30, 2015 | Jun. 30, 2016 | Jun. 30, 2015
Interest income: |  |  |  |
Education loans | $ 1,020 | $ 1,060 | $ 2,065 | $ 2,153
Other loans | 2 | 2 | 3 | 4
Cash and investments | 6 | 2 | 12 | 4
Total interest income | 1,028 | 1,064 | 2,080 | 2,161
Total interest expense | 599 | 515 | 1,165 | 1,029
Net interest income (loss) | 429 | 549 | 915 | 1,132
Less: provisions for loan losses | 110 | 198 | 221 | 323
Net interest income (loss) after provisions for loan losses | 319 | 351 | 694 | 809
Other income (loss): |  |  |  |
Servicing revenue | 71 | 106 | 154 | 182
Asset recovery and business processing revenue | 101 | 99 | 191 | 188
Other income (loss) | (49) | (11) | (62) | 68
Gains on sales of loans and investments |  | 7 |  | 12
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | 123 | 201 | 283 | 450
Expenses: |  |  |  |
Direct operating expenses | 175 | 170 | 362 | 338
Overhead expenses | 55 | 55 | 116 | 118
Total operating expenses | 230 | 225 | 478 | 456
Goodwill and acquired intangible asset impairment and amortization | 6 | 3 | 10 | 4
Restructuring and other reorganization expenses |  | 29 |  | 32
Total expenses | 236 | 257 | 488 | 492
Income (loss) from continuing operations, before income tax expense (benefit) | 206 | 295 | 489 | 767
Income tax expense (benefit) | 81 | 113 | 184 | 293
Net income (loss) from continuing operations | 125 | 182 | 305 | 474
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | 125 | 182 | 305 | 474
Reclassifications [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 56 | 163 | 195 | 325
Total interest income | 56 | 163 | 195 | 325
Total interest expense | 9 | 7 | 18 | 16
Net interest income (loss) | 47 | 156 | 177 | 309
Net interest income (loss) after provisions for loan losses | 47 | 156 | 177 | 309
Other income (loss): |  |  |  |
Other income (loss) | (47) | (156) | (177) | (309)
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | (47) | (156) | (177) | (309)
Expenses: |  |  |  |
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Additions/ (Subtractions) [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | (26) | (59) | (86) | (118)
Total interest income | (26) | (59) | (86) | (118)
Net interest income (loss) | (26) | (59) | (86) | (118)
Net interest income (loss) after provisions for loan losses | (26) | (59) | (86) | (118)
Other income (loss): |  |  |  |
Other income (loss) | (6) | 142 | 108 | 367
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | (6) | 142 | 108 | 367
Expenses: |  |  |  |
Goodwill and acquired intangible asset impairment and amortization | 6 | 3 | 10 | 4
Restructuring and other reorganization expenses |  | 29 |  | 32
Total expenses | 6 | 32 | 10 | 36
Income (loss) from continuing operations, before income tax expense (benefit) | (38) | 51 | 12 | 213
Income tax expense (benefit) | (9) | 23 | 8 | 87
Net income (loss) from continuing operations | (29) | 28 | 4 | 126
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | (29) | 28 | 4 | 126
Total Adjustments [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 30 | 104 | 109 | 207
Total interest income | 30 | 104 | 109 | 207
Total interest expense | 9 | 7 | 18 | 16
Net interest income (loss) | 21 | 97 | 91 | 191
Net interest income (loss) after provisions for loan losses | 21 | 97 | 91 | 191
Other income (loss): |  |  |  |
Other income (loss) | (53) | (14) | (69) | 58
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | (53) | (14) | (69) | 58
Expenses: |  |  |  |
Total operating expenses | 0 | 0 | 0 | 0
Goodwill and acquired intangible asset impairment and amortization | 6 | 3 | 10 | 4
Restructuring and other reorganization expenses |  | 29 |  | 32
Total expenses | 6 | 32 | 10 | 36
Income (loss) from continuing operations, before income tax expense (benefit) | (38) | 51 | 12 | 213
Income tax expense (benefit) | (9) | 23 | 8 | 87
Net income (loss) from continuing operations | (29) | 28 | 4 | 126
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | (29) | 28 | 4 | 126
Operating Segments [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 990 | 956 | 1,956 | 1,946
Other loans | 2 | 2 | 3 | 4
Cash and investments | 6 | 2 | 12 | 4
Total interest income | 998 | 960 | 1,971 | 1,954
Total interest expense | 590 | 508 | 1,147 | 1,013
Net interest income (loss) | 408 | 452 | 824 | 941
Less: provisions for loan losses | 110 | 198 | 221 | 323
Net interest income (loss) after provisions for loan losses | 298 | 254 | 603 | 618
Other income (loss): |  |  |  |
Servicing revenue | 71 | 106 | 154 | 182
Asset recovery and business processing revenue | 101 | 99 | 191 | 188
Other income (loss) | 4 | 3 | 7 | 10
Gains on sales of loans and investments |  | 7 |  | 12
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | 176 | 215 | 352 | 392
Expenses: |  |  |  |
Direct operating expenses | 175 | 170 | 362 | 338
Overhead expenses | 55 | 55 | 116 | 118
Total operating expenses | 230 | 225 | 478 | 456
Total expenses | 230 | 225 | 478 | 456
Income (loss) from continuing operations, before income tax expense (benefit) | 244 | 244 | 477 | 554
Income tax expense (benefit) | 90 | 90 | 176 | 206
Net income (loss) from continuing operations | 154 | 154 | 301 | 348
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | 154 | 154 | 301 | 348
Operating Segments [Member] | FFELP Loans Segment [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 588 | 522 | 1,143 | 1,055
Cash and investments | 5 | 1 | 8 | 3
Total interest income | 593 | 523 | 1,151 | 1,058
Total interest expense | 388 | 309 | 746 | 611
Net interest income (loss) | 205 | 214 | 405 | 447
Less: provisions for loan losses | 10 | 7 | 17 | 12
Net interest income (loss) after provisions for loan losses | 195 | 207 | 388 | 435
Other income (loss): |  |  |  |
Servicing revenue | 14 | 45 | 31 | 63
Gains on sales of loans and investments |  | 7 |  | 12
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | 14 | 52 | 31 | 75
Expenses: |  |  |  |
Direct operating expenses | 101 | 112 | 206 | 227
Total operating expenses | 101 | 112 | 206 | 227
Total expenses | 101 | 112 | 206 | 227
Income (loss) from continuing operations, before income tax expense (benefit) | 108 | 147 | 213 | 283
Income tax expense (benefit) | 40 | 54 | 79 | 106
Net income (loss) from continuing operations | 68 | 93 | 134 | 177
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | 68 | 93 | 134 | 177
Operating Segments [Member] | Private Education Loans Segment [Member] |  |  |  |
Interest income: |  |  |  |
Education loans | 402 | 434 | 813 | 891
Cash and investments |  |  | 1 |
Total interest income | 402 | 434 | 814 | 891
Total interest expense | 173 | 171 | 345 | 345
Net interest income (loss) | 229 | 263 | 469 | 546
Less: provisions for loan losses | 100 | 191 | 204 | 311
Net interest income (loss) after provisions for loan losses | 129 | 72 | 265 | 235
Other income (loss): |  |  |  |
Servicing revenue | 3 | 6 | 8 | 12
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | 3 | 6 | 8 | 12
Expenses: |  |  |  |
Direct operating expenses | 41 | 43 | 84 | 89
Total operating expenses | 41 | 43 | 84 | 89
Total expenses | 41 | 43 | 84 | 89
Income (loss) from continuing operations, before income tax expense (benefit) | 91 | 35 | 189 | 158
Income tax expense (benefit) | 34 | 13 | 70 | 58
Net income (loss) from continuing operations | 57 | 22 | 119 | 100
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | 57 | 22 | 119 | 100
Operating Segments [Member] | Business Services Segment [Member] |  |  |  |
Other income (loss): |  |  |  |
Servicing revenue | 153 | 163 | 315 | 326
Asset recovery and business processing revenue | 101 | 99 | 191 | 188
Other income (loss) |  |  |  | 2
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | 254 | 262 | 506 | 516
Expenses: |  |  |  |
Direct operating expenses | 125 | 117 | 258 | 233
Total operating expenses | 125 | 117 | 258 | 233
Total expenses | 125 | 117 | 258 | 233
Income (loss) from continuing operations, before income tax expense (benefit) | 129 | 145 | 248 | 283
Income tax expense (benefit) | 48 | 54 | 91 | 106
Net income (loss) from continuing operations | 81 | 91 | 157 | 177
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | 81 | 91 | 157 | 177
Operating Segments [Member] | Other Segment [Member] |  |  |  |
Interest income: |  |  |  |
Other loans | 2 | 2 | 3 | 4
Cash and investments | 1 | 1 | 3 | 1
Total interest income | 3 | 3 | 6 | 5
Total interest expense | 29 | 28 | 56 | 57
Net interest income (loss) | (26) | (25) | (50) | (52)
Net interest income (loss) after provisions for loan losses | (26) | (25) | (50) | (52)
Other income (loss): |  |  |  |
Other income (loss) | 4 | 3 | 7 | 8
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | 4 | 3 | 7 | 8
Expenses: |  |  |  |
Direct operating expenses | 7 | 6 | 14 | 8
Overhead expenses | 55 | 55 | 116 | 118
Total operating expenses | 62 | 61 | 130 | 126
Total expenses | 62 | 61 | 130 | 126
Income (loss) from continuing operations, before income tax expense (benefit) | (84) | (83) | (173) | (170)
Income tax expense (benefit) | (32) | (31) | (64) | (64)
Net income (loss) from continuing operations | (52) | (52) | (109) | (106)
Income (loss) from discontinued operations, net of tax expense (benefit) | 0 | 0 | 0 | 0
Net income (loss) | (52) | (52) | (109) | (106)
Eliminations [Member] |  |  |  |
Other income (loss): |  |  |  |
Servicing revenue | (99) | (108) | (200) | (219)
Gains on debt repurchases | 0 | 0 | 0 | 0
Total other income | (99) | (108) | (200) | (219)
Expenses: |  |  |  |
Direct operating expenses | (99) | (108) | (200) | (219)
Total operating expenses | (99) | (108) | (200) | (219)
Total expenses | (99) | (108) | (200) | (219)
Income (loss) from discontinued operations, net of tax expense (benefit) | $ 0 | $ 0 | $ 0 | $ 0

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