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Allowance for Credit Losses - Allowance and Recorded Investments in Loans (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Dec. 31, 2019 | Jan. 01, 2020
Allowance for Credit Losses |  |  |  |  |  |
Beginning balance | $ 1,929,323 | $ 383,997 | $ 441,912 | $ 341,121 | $ 341,121 |
Provision for current period | (90,014) |  | 338,120 |  |  |
Loan sale reduction to provision | (42,916) |  | (204,709) |  |  |
Total provision | (132,930) | 98,314 | 133,411 | 256,889 |  |
Net charge-offs: |  |  |  |  |  |
Charge-offs | (60,666) | (76,227) | (178,120) | (205,916) |  |
Recoveries | 6,896 | 8,322 | 23,282 | 22,312 |  |
Net charge-offs | 53,770 | 67,905 | 154,838 | 183,604 |  |
Loan sales | (108,534) |  | (108,534) |  |  |
Ending Balance | 1,734,559 | 414,406 | 1,734,559 | 414,406 | 441,912 |
Allowance: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 138,663 | 171,884 | 138,663 | 171,884 |  |
Ending balance: collectively evaluated for impairment | 1,595,896 | 242,522 | 1,595,896 | 242,522 |  |
Loans: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 1,495,161 | 1,474,819 | 1,495,161 | 1,474,819 |  |
Ending balance: collectively evaluated for impairment | 21,876,262 | 23,575,351 | 21,876,262 | 23,575,351 |  |
Provision for loan losses | (81,710) |  | 134,374 |  |  |
Provision for unfunded commitments | 129,290 |  | 276,094 |  |  |
Total Private Education Loan provision for credit losses | 47,580 |  | 410,468 |  |  |
Private Education Loan provision for credit losses, other impacts | (51,220) |  | (963) |  |  |
Less: provisions for credit losses | (3,640) | 99,526 | 409,505 | 256,691 |  |
Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Transfer from unfunded commitment liability | 100,470 |  | 279,555 |  |  |
Net charge-offs: |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  | $ 1,143,053
FFELP Loans |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Beginning balance | 4,385 | 1,734 | 1,633 | 977 | 977 |
Provision for current period | 67 |  | 277 |  |  |
Loan sale reduction to provision | 0 |  | 0 |  |  |
Total provision | 67 | 158 | 277 | 1,320 |  |
Net charge-offs: |  |  |  |  |  |
Charge-offs | (89) | (203) | (399) | (608) |  |
Recoveries | 0 | 0 | 0 | 0 |  |
Net charge-offs | 89 | 203 | 399 | 608 |  |
Loan sales | 0 |  | 0 |  |  |
Ending Balance | 4,363 | 1,689 | 4,363 | 1,689 | 1,633 |
Allowance: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | 4,363 | 1,689 | 4,363 | 1,689 |  |
Loans: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | $ 745,556 | $ 798,168 | $ 745,556 | $ 798,168 |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 0.07% | 0.13% | 0.10% | 0.13% |  |
Allowance as a percentage of the ending total loan balance | 0.59% | 0.21% | 0.59% | 0.21% |  |
Allowance as a percentage of the ending loans in repayment | 0.77% | 0.27% | 0.77% | 0.27% |  |
Allowance coverage of net charge-offs (annualized) | 12.26 | 2.08 | 8.20 | 2.08 |  |
Ending total loans, gross | $ 745,556 | $ 798,168 | $ 745,556 | $ 798,168 |  |
Average loans in repayment | 510,809 | 621,706 | 546,443 | 636,538 |  |
Ending loans in repayment | 564,442 | 631,626 | 564,442 | 631,626 |  |
Private Education Loan provision for credit losses, other impacts | 67 |  | 277 |  |  |
FFELP Loans | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Transfer from unfunded commitment liability | 0 |  | 0 |  |  |
Net charge-offs: |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  | 2,852
Private Education Loans |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Beginning balance | 1,760,559 | 307,968 | 374,300 | 277,943 | 277,943 |
Provision for current period | (81,710) |  | 296,167 |  |  |
Loan sale reduction to provision | 0 |  | (161,793) |  |  |
Total provision | (81,710) | 84,110 | 134,374 | 197,289 |  |
Net charge-offs: |  |  |  |  |  |
Charge-offs | (55,298) | (56,398) | (138,546) | (151,357) |  |
Recoveries | 4,790 | 6,864 | 18,298 | 18,669 |  |
Net charge-offs | 50,508 | 49,534 | 120,248 | 132,688 |  |
Loan sales | 0 |  | 0 |  |  |
Ending Balance | 1,728,811 | 342,544 | 1,728,811 | 342,544 | 374,300 |
Allowance: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 138,663 | 171,884 | 138,663 | 171,884 |  |
Ending balance: collectively evaluated for impairment | 1,590,148 | 170,660 | 1,590,148 | 170,660 |  |
Loans: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 1,495,161 | 1,474,819 | 1,495,161 | 1,474,819 |  |
Ending balance: collectively evaluated for impairment | $ 21,119,166 | $ 21,645,350 | $ 21,119,166 | $ 21,645,350 |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 1.33% | 1.27% | 1.05% | 1.15% |  |
Allowance as a percentage of the ending total loan balance | 7.64% | 1.48% | 7.64% | 1.48% |  |
Allowance as a percentage of the ending loans in repayment | 10.91% | 2.13% | 10.91% | 2.13% |  |
Allowance coverage of net charge-offs (annualized) | 8.56 | 1.73 | 10.78 | 1.94 |  |
Ending total loans, gross | $ 22,614,327 | $ 23,120,169 | $ 22,614,327 | $ 23,120,169 |  |
Average loans in repayment | 15,182,703 | 15,632,028 | 15,336,253 | 15,351,188 |  |
Ending loans in repayment | 15,853,309 | 16,072,979 | 15,853,309 | 16,072,979 |  |
Private Education Loans | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Transfer from unfunded commitment liability | 100,470 |  | 279,555 |  |  |
Net charge-offs: |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  | 1,060,830
Personal Loans |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Beginning balance | 163,337 | 74,295 | 65,877 | 62,201 | 62,201 |
Provision for current period | (8,762) |  | 40,485 |  |  |
Loan sale reduction to provision | (42,916) |  | (42,916) |  |  |
Total provision | (51,678) | 14,046 | (2,431) | 58,280 |  |
Net charge-offs: |  |  |  |  |  |
Charge-offs | (5,231) | (19,626) | (39,079) | (53,951) |  |
Recoveries | 2,106 | 1,458 | 4,984 | 3,643 |  |
Net charge-offs | 3,125 | 18,168 | 34,095 | 50,308 |  |
Loan sales | (108,534) |  | (108,534) |  |  |
Ending Balance | 0 | 70,173 | 0 | 70,173 | 65,877 |
Allowance: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | 0 | 70,173 | 0 | 70,173 |  |
Loans: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | $ 0 | $ 1,131,833 | $ 0 | $ 1,131,833 |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 0.00% | 6.42% | 0.00% | 5.82% |  |
Allowance as a percentage of the ending total loan balance | 0.00% | 6.20% | 0.00% | 6.20% |  |
Allowance as a percentage of the ending loans in repayment | 0.00% | 6.20% | 0.00% | 6.20% |  |
Allowance coverage of net charge-offs (annualized) | 0 | 0.97 | 0 | 1.05 |  |
Ending total loans, gross | $ 0 | $ 1,131,833 | $ 0 | $ 1,131,833 |  |
Average loans in repayment | 0 | 1,131,965 | 0 | 1,152,555 |  |
Ending loans in repayment | 0 | $ 1,131,833 | 0 | $ 1,131,833 |  |
Private Education Loan provision for credit losses, other impacts | (51,678) |  | (2,431) |  |  |
Personal Loans | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Transfer from unfunded commitment liability | 0 |  | 0 |  |  |
Net charge-offs: |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  | 79,183
Credit Cards |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Beginning balance | 1,042 |  | 102 |  |  |
Provision for current period | 391 |  | 1,191 |  |  |
Loan sale reduction to provision | 0 |  | 0 |  |  |
Total provision | 391 |  | 1,191 |  |  |
Net charge-offs: |  |  |  |  |  |
Charge-offs | (48) |  | (96) |  |  |
Recoveries | 0 |  | 0 |  |  |
Net charge-offs | 48 |  | 96 |  |  |
Loan sales | 0 |  | 0 |  |  |
Ending Balance | 1,385 |  | 1,385 |  | $ 102 |
Allowance: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  | 0 |  |  |
Ending balance: collectively evaluated for impairment | 1,385 |  | 1,385 |  |  |
Loans: |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  | 0 |  |  |
Ending balance: collectively evaluated for impairment | $ 11,540 |  | $ 11,540 |  |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 1.73% |  | 1.51% |  |  |
Allowance as a percentage of the ending total loan balance | 12.00% |  | 12.00% |  |  |
Allowance as a percentage of the ending loans in repayment | 12.00% |  | 12.00% |  |  |
Allowance coverage of net charge-offs (annualized) | 7.21 |  | 10.82 |  |  |
Ending total loans, gross | $ 11,540 |  | $ 11,540 |  |  |
Average loans in repayment | 11,103 |  | 8,499 |  |  |
Ending loans in repayment | 11,540 |  | 11,540 |  |  |
Private Education Loan provision for credit losses, other impacts | 391 |  | 1,191 |  |  |
Credit Cards | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |
Allowance for Credit Losses |  |  |  |  |  |
Transfer from unfunded commitment liability | $ 0 |  | $ 0 |  |  |
Net charge-offs: |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  | $ 188

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