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Allowance for Loan Losses - Allowance and Recorded Investments in Loans (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended | 12 Months Ended |
--- | --- | --- | --- | ---
Jun. 30, 2020 | Mar. 31, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019 | Jan. 01, 2020
Allowance for Loan Losses |  |  |  |  |  |  |
Beginning balance | $ 1,673,324 | $ 441,912 | $ 358,325 | $ 441,912 | $ 341,121 | $ 341,121 |
Provision for current period | 253,146 |  |  | 428,134 |  |  |
Loan sale reduction to provision | 0 |  |  | (161,793) |  |  |
Total provision | 253,146 |  | 92,915 | 266,341 | 158,575 |  |
Net charge-offs: |  |  |  |  |  |  |
Charge-offs | (46,505) |  | (74,627) | (117,454) | (129,689) |  |
Recoveries | 6,868 |  | 7,384 | 16,386 | 13,990 |  |
Net charge-offs | 39,637 |  | 67,243 | 101,068 | 115,699 |  |
Ending Balance | 1,929,323 | 1,673,324 | 383,997 | 1,929,323 | 383,997 | 441,912 |
Allowance: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 160,234 |  | 146,403 | 160,234 | 146,403 |  |
Ending balance: collectively evaluated for impairment | 1,769,089 |  | 237,594 | 1,769,089 | 237,594 |  |
Loans: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 1,520,240 |  | 1,411,189 | 1,520,240 | 1,411,189 |  |
Ending balance: collectively evaluated for impairment | 21,502,357 |  | 22,164,795 | 21,502,357 | 22,164,795 |  |
Provisions for credit losses for new loan commitments made during the quarter | 98,741 |  |  | 146,804 |  |  |
Total provision for allowance for loan losses | 253,146 |  |  | 266,341 |  |  |
Provisions for credit losses reported in consolidated statements of operations | 351,887 |  | 93,375 | 413,145 | 157,165 |  |
Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |  |
Allowance for Loan Losses |  |  |  |  |  |  |
Transfer from unfunded commitment liability | 42,490 |  |  | 179,085 |  |  |
Net charge-offs: |  |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  |  | $ 1,143,053
FFELP Loans |  |  |  |  |  |  |
Allowance for Loan Losses |  |  |  |  |  |  |
Beginning balance | 4,296 | 1,633 | 1,760 | 1,633 | 977 | 977 |
Provision for current period | 173 |  |  | 210 |  |  |
Loan sale reduction to provision | 0 |  |  | 0 |  |  |
Total provision | 173 |  | 145 | 210 | 1,162 |  |
Net charge-offs: |  |  |  |  |  |  |
Charge-offs | (84) |  | (171) | (310) | (405) |  |
Recoveries | 0 |  | 0 | 0 | 0 |  |
Net charge-offs | 84 |  | 171 | 310 | 405 |  |
Ending Balance | 4,385 | 4,296 | 1,734 | 4,385 | 1,734 | 1,633 |
Allowance: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | 4,385 |  | 1,734 | 4,385 | 1,734 |  |
Loans: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | $ 754,340 |  | $ 812,500 | $ 754,340 | $ 812,500 |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 0.07% |  | 0.11% | 0.11% | 0.13% |  |
Allowance as a percentage of the ending total loan balance | 0.58% |  | 0.21% | 0.58% | 0.21% |  |
Allowance as a percentage of the ending loans in repayment | 0.97% |  | 0.28% | 0.97% | 0.28% |  |
Allowance coverage of net charge-offs (annualized) | 13.05 |  | 2.54 | 7.07 | 2.14 |  |
Ending total loans, gross | $ 754,340 |  | $ 812,500 | $ 754,340 | $ 812,500 |  |
Average loans in repayment | 513,418 |  | 634,932 | 553,402 | 642,693 |  |
Ending loans in repayment | 452,617 |  | 620,292 | 452,617 | 620,292 |  |
FFELP Loans | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |  |
Allowance for Loan 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 Loan Losses |  |  |  |  |  |  |
Beginning balance | 1,515,781 | 374,300 | 285,946 | 374,300 | 277,943 | 277,943 |
Provision for current period | 228,535 |  |  | 377,877 |  |  |
Loan sale reduction to provision | 0 |  |  | (161,793) |  |  |
Total provision | 228,535 |  | 71,296 | 216,084 | 113,179 |  |
Net charge-offs: |  |  |  |  |  |  |
Charge-offs | (31,779) |  | (55,382) | (83,248) | (94,959) |  |
Recoveries | 5,532 |  | 6,108 | 13,508 | 11,805 |  |
Net charge-offs | 26,247 |  | 49,274 | 69,740 | 83,154 |  |
Ending Balance | 1,760,559 | 1,515,781 | 307,968 | 1,760,559 | 307,968 | 374,300 |
Allowance: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 160,234 |  | 146,403 | 160,234 | 146,403 |  |
Ending balance: collectively evaluated for impairment | 1,600,325 |  | 161,565 | 1,600,325 | 161,565 |  |
Loans: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 1,520,240 |  | 1,411,189 | 1,520,240 | 1,411,189 |  |
Ending balance: collectively evaluated for impairment | $ 19,965,225 |  | $ 20,217,658 | $ 19,965,225 | $ 20,217,658 |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 0.75% |  | 1.29% | 0.91% | 1.09% |  |
Allowance as a percentage of the ending total loan balance | 8.19% |  | 1.42% | 8.19% | 1.42% |  |
Allowance as a percentage of the ending loans in repayment | 12.13% |  | 2.01% | 12.13% | 2.01% |  |
Allowance coverage of net charge-offs (annualized) | 16.77 |  | 1.56 | 12.62 | 1.85 |  |
Ending total loans, gross | $ 21,485,465 |  | $ 21,628,847 | $ 21,485,465 | $ 21,628,847 |  |
Average loans in repayment | 14,011,841 |  | 15,241,574 | 15,306,349 | 15,188,003 |  |
Ending loans in repayment | 14,512,723 |  | 15,332,251 | 14,512,723 | 15,332,251 |  |
Private Education Loans | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |  |
Allowance for Loan Losses |  |  |  |  |  |  |
Transfer from unfunded commitment liability | 42,490 |  |  | 179,085 |  |  |
Net charge-offs: |  |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  |  | 1,060,830
Personal Loans |  |  |  |  |  |  |
Allowance for Loan Losses |  |  |  |  |  |  |
Beginning balance | 152,673 | 65,877 | 70,619 | 65,877 | 62,201 | 62,201 |
Provision for current period | 23,929 |  |  | 49,247 |  |  |
Loan sale reduction to provision | 0 |  |  | 0 |  |  |
Total provision | 23,929 |  | 21,474 | 49,247 | 44,234 |  |
Net charge-offs: |  |  |  |  |  |  |
Charge-offs | (14,601) |  | (19,074) | (33,848) | (34,325) |  |
Recoveries | 1,336 |  | 1,276 | 2,878 | 2,185 |  |
Net charge-offs | 13,265 |  | 17,798 | 30,970 | 32,140 |  |
Ending Balance | 163,337 | 152,673 | 74,295 | 163,337 | 74,295 | 65,877 |
Allowance: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | 163,337 |  | 74,295 | 163,337 | 74,295 |  |
Loans: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  | 0 | 0 | 0 |  |
Ending balance: collectively evaluated for impairment | $ 772,086 |  | $ 1,134,637 | $ 772,086 | $ 1,134,637 |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 6.87% |  | 6.20% | 7.13% | 5.53% |  |
Allowance as a percentage of the ending total loan balance | 21.16% |  | 6.55% | 21.16% | 6.55% |  |
Allowance as a percentage of the ending loans in repayment | 22.46% |  | 6.55% | 22.46% | 6.55% |  |
Allowance coverage of net charge-offs (annualized) | 3.08 |  | 1.04 | 2.64 | 1.16 |  |
Ending total loans, gross | $ 772,086 |  | $ 1,134,637 | $ 772,086 | $ 1,134,637 |  |
Average loans in repayment | 772,137 |  | 1,148,444 | 869,133 | 1,161,761 |  |
Ending loans in repayment | 727,214 |  | $ 1,134,637 | 727,214 | $ 1,134,637 |  |
Personal Loans | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |  |
Allowance for Loan 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 Loan Losses |  |  |  |  |  |  |
Beginning balance | 574 | 102 |  | 102 |  |  |
Provision for current period | 509 |  |  | 800 |  |  |
Loan sale reduction to provision | 0 |  |  | 0 |  |  |
Total provision | 509 |  |  | 800 |  |  |
Net charge-offs: |  |  |  |  |  |  |
Charge-offs | (41) |  |  | (48) |  |  |
Recoveries | 0 |  |  | 0 |  |  |
Net charge-offs | 41 |  |  | 48 |  |  |
Ending Balance | 1,042 | $ 574 |  | 1,042 |  | $ 102 |
Allowance: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  |  | 0 |  |  |
Ending balance: collectively evaluated for impairment | 1,042 |  |  | 1,042 |  |  |
Loans: |  |  |  |  |  |  |
Ending balance: individually evaluated for impairment | 0 |  |  | 0 |  |  |
Ending balance: collectively evaluated for impairment | $ 10,706 |  |  | $ 10,706 |  |  |
Net charge-offs as a percentage of average loans in repayment (annualized) | 1.77% |  |  | 1.31% |  |  |
Allowance as a percentage of the ending total loan balance | 9.73% |  |  | 9.73% |  |  |
Allowance as a percentage of the ending loans in repayment | 9.73% |  |  | 9.73% |  |  |
Allowance coverage of net charge-offs (annualized) | 6.35 |  |  | 10.85 |  |  |
Ending total loans, gross | $ 10,706 |  |  | $ 10,706 |  |  |
Average loans in repayment | 9,265 |  |  | 7,326 |  |  |
Ending loans in repayment | 10,706 |  |  | 10,706 |  |  |
Credit Cards | Cumulative Effect, Period Of Adoption, Adjustment |  |  |  |  |  |  |
Allowance for Loan Losses |  |  |  |  |  |  |
Transfer from unfunded commitment liability | $ 0 |  |  | $ 0 |  |  |
Net charge-offs: |  |  |  |  |  |  |
Day 1 adjustment for the adoption of CECL |  |  |  |  |  |  | $ 188

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