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Variable Interest Entities Special Purpose Entities, including Variable Interest Entities - Summary of Assets and Liabilities (Details) $ in Millions | Dec. 31, 2021 USD ($) Entity | Dec. 31, 2020 USD ($) Entity | Dec. 31, 2019 USD ($)
--- | --- | --- | ---
Available-for-sale Securities, Amortized Cost Basis | $ 2,140 | $ 2,807 |
Available-for-sale Securities | 2,265 |  |
Restricted Cash | 5 | 13 | $ 55
Derivative assets | 76 | 93 |
Other assets | 68 | 68 |
Assets | 12,303 | 13,220 |
Accrued interest payable | 576 | 517 |
Long-term debt | 2,230 | 2,739 |
Derivative liabilities | 95 | 114 |
Liabilities | 11,187 | 12,074 |
Variable Interest Entity [Member] |  |  |
Available-for-sale Securities | 3,455 | 3,354 |
Restricted Cash | 2 | 2 | $ 2
Loans, at fair value | 2,718 | 2,998 |
Derivative assets | 38 | 41 |
Other assets | 2 | 2 |
Assets | 6,216 | 6,398 |
Long-term Debt | 4,056 | 4,324 |
Long-term Debt, at par less amortized discount | 160 | 169 |
Long-term debt | 4,216 | 4,493 |
Derivative liabilities | 1,940 | 1,835 |
Liabilities | 6,156 | 6,328 |
Loans, Unpaid principal balance | 2,363 | 2,546 |
Long-term debt, Unpaid principal balance | 3,579 | 3,769 |
Variable Interest Entity [Member] | Ambac UK [Member] |  |  |
Available-for-sale Securities | 3,320 | 3,215 |
Restricted Cash | 1 | 1 |
Loans, at fair value | 2,718 | 2,998 |
Derivative assets | 38 | 41 |
Other assets | 0 | 0 |
Assets | 6,077 | 6,255 |
Long-term Debt | 4,056 | 4,324 |
Long-term Debt, at par less amortized discount | 0 | 0 |
Long-term debt | 4,056 | 4,324 |
Derivative liabilities | 1,940 | 1,835 |
Liabilities | 5,996 | 6,159 |
Variable Interest Entity [Member] | Ambac Assurance [Member] |  |  |
Available-for-sale Securities | 136 | 139 |
Restricted Cash | 1 | 1 |
Loans, at fair value | 0 | 0 |
Derivative assets | 0 | 0 |
Other assets | 2 | 2 |
Assets | 139 | 143 |
Long-term Debt | 0 | 0 |
Long-term Debt, at par less amortized discount | 160 | 169 |
Long-term debt | 160 | 169 |
Derivative liabilities | 0 | 0 |
Liabilities | 160 | 169 |
Variable Interest Entity [Member] | Corporate Debt Securities [Member] |  |  |
Available-for-sale Securities | 3,320 | 3,215 |
Variable Interest Entity [Member] | Corporate Debt Securities [Member] | Ambac UK [Member] |  |  |
Available-for-sale Securities | 3,320 | 3,215 |
Variable Interest Entity [Member] | Corporate Debt Securities [Member] | Ambac Assurance [Member] |  |  |
Available-for-sale Securities | 0 | 0 |
Variable Interest Entity [Member] | Municipal Bonds [Member] |  |  |
Available-for-sale Securities, Amortized Cost Basis | 106 | 113 |
Available-for-sale Securities | 136 | 139 |
Variable Interest Entity [Member] | Municipal Bonds [Member] | Ambac UK [Member] |  |  |
Available-for-sale Securities | 0 | 0 |
Variable Interest Entity [Member] | Municipal Bonds [Member] | Ambac Assurance [Member] |  |  |
Available-for-sale Securities | $ 136 | $ 139 |
Consolidated Entities [Member] |  |  |
Number of consolidated Variable Interest Entities | Entity | 6 | 6 |
Consolidated Entities [Member] | Ambac UK [Member] |  |  |
Number of consolidated Variable Interest Entities | Entity | 5 | 5 |
Consolidated Entities [Member] | Ambac Assurance [Member] |  |  |
Number of consolidated Variable Interest Entities | Entity | 1 | 1 |

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