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Allowance for Loan Losses - Age Analysis of Past Due Loans Delinquencies (Detail) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Sep. 30, 2022 | Sep. 30, 2021 | Dec. 31, 2021 | Jun. 30, 2022 | Jun. 30, 2021 | Dec. 31, 2020
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loan allowance for losses | $ (1,085) | $ (1,249) | $ (1,271) | $ (1,166) | $ (1,253) | $ (1,377)
FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 47,124 | 54,619 |  |  |  |
Loan allowance for losses | (233) | (269) | (262) | $ (245) | $ (277) | $ (288)
Loans, net | 46,891 |  | 52,641 |  |  |
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 6,796 | 7,411 | 7,256 |  |  |
Loan allowance for losses | (666) | (814) | (829) |  |  |
Loans, net | $ 6,130 | $ 6,597 | $ 6,427 |  |  |
Dimensions of concentration risk | 100.00% | 100.00% | 100.00% |  |  |
Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | $ 13,207 | $ 13,587 | $ 13,924 |  |  |
Loan allowance for losses | (186) | (166) | (180) |  |  |
Loans, net | $ 13,021 | $ 13,421 | $ 13,744 |  |  |
Dimensions of concentration risk | 100.00% | 100.00% | 100.00% |  |  |
Credit Concentration Risk [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | $ 47,124 | $ 54,619 | $ 52,903 |  |  |
Loan allowance for losses | (233) | (269) | (262) |  |  |
Loans, net | $ 46,891 | $ 54,350 | $ 52,641 |  |  |
Dimensions of concentration risk | 100.00% | 100.00% | 100.00% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Current [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 87.80% | 91.60% | 91.00% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Current [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 99.40% | 99.60% | 99.60% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Current [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 81.40% | 91.50% | 89.40% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 31 to 60 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 4.20% | 3.50% | 3.00% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 31 to 60 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 0.30% | 0.20% | 0.20% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 31 to 60 Days Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 5.10% | 2.70% | 3.80% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 61 to 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 2.30% | 1.90% | 1.80% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 61 to 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 0.10% | 0.10% | 0.10% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 61 to 90 Days Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 3.40% | 1.50% | 2.00% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 5.70% | 3.00% | 4.20% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 0.20% | 0.10% | 0.10% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, 90 Days Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Loans delinquent, percentage | 10.10% | 4.30% | 4.80% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Loans In Repayment [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 93.40% | 88.20% | 91.20% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Loans In Repayment [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 97.90% | 97.60% | 98.20% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Loans In Repayment [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 80.10% | 80.90% | 83.90% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Delinquent Loans in Repayment [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 12.20% | 8.40% | 9.00% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Delinquent Loans in Repayment [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 0.60% | 0.40% | 0.40% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Delinquent Loans in Repayment [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 18.60% | 8.50% | 10.60% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Forbearance, Loans In Repayment [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 4.30% | 9.30% | 6.30% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Forbearance, Loans In Repayment [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 0.70% | 1.10% | 0.60% |  |  |
Credit Concentration Risk [Member] | Financing Receivables, Forbearance, Loans In Repayment [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Dimensions of concentration risk | 16.40% | 15.40% | 12.40% |  |  |
School/Grace/Deferment [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | $ 164 | $ 210 | $ 194 |  |  |
School/Grace/Deferment [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 184 | 179 | 167 |  |  |
School/Grace/Deferment [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 1,983 | 2,430 | 2,220 |  |  |
Forbearance [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 284 | 667 | 446 |  |  |
Forbearance [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 87 | 147 | 89 |  |  |
Forbearance [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 7,410 | 8,029 | 6,292 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 6,348 | 6,534 | 6,616 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 12,936 | 13,261 | 13,668 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 37,731 | 44,160 | 44,391 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financing Asset, Not Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 5,573 | 5,988 | 6,023 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financing Asset, Not Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 12,853 | 13,208 | 13,611 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financing Asset, Not Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 30,720 | 40,404 | 39,679 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 31 to 60 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 269 | 224 | 199 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 31 to 60 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 36 | 23 | 23 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 31 to 60 Days Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 1,917 | 1,181 | 1,696 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 61 to 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 143 | 124 | 120 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 61 to 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 16 | 12 | 11 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 61 to 90 Days Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 1,291 | 665 | 904 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 363 | 198 | 274 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 90 Days Past Due [Member] | Accounts Receivable [Member] | Private Education Loans - Non-TDRs [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | 31 | 18 | 23 |  |  |
Repayment [Member] | Credit Concentration Risk [Member] | Financial Asset, 90 Days Past Due [Member] | Accounts Receivable [Member] | FFELP Loans [Member] |  |  |  |  |  |
Loans in repayment and percentage of each status: |  |  |  |  |  |
Total Loans, gross | $ 3,803 | $ 1,910 | $ 2,112 |  |  |

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