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Fair Value Of Financial Instruments (Fair Value Hierarchy Table Presents The Company's Assets And Liabilities At Fair Value Not Recorded On The Company's Consolidated Balance Sheet) (Detail) - USD ($) $ in Millions | Jun. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Variable Interest Entity Primary Beneficiary [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Variable interest entity notes | $ 450 | $ 623
Carrying Reported Amount Fair Value Disclosure [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Long-term debt | 2,283 | 2,229
Medium-term notes | 532 | 598
Investment agreements | 269 | 269
Total liabilities | 3,213 | 3,369
Gross | (235) | (282)
Ceded recoverable (liability) | (20) | (17)
Carrying Reported Amount Fair Value Disclosure [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Variable interest entity notes | 129 | 273
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Long-term debt | 595 | 631
Medium-term notes | 328 | 396
Investment agreements | 358 | 376
Total liabilities | 1,414 | 1,679
Gross | 921 | 811
Ceded recoverable (liability) | 47 | 45
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Variable interest entity notes | 133 | 276
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 1 [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Long-term debt | 0 | 0
Medium-term notes | 0 | 0
Investment agreements | 0 | 0
Total liabilities | 0 | 0
Gross | 0 | 0
Ceded recoverable (liability) | 0 | 0
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 1 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Variable interest entity notes | 0 | 0
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Long-term debt | 595 | 631
Medium-term notes | 0 | 0
Investment agreements | 0 | 0
Total liabilities | 728 | 907
Gross | 0 | 0
Ceded recoverable (liability) | 0 | 0
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 2 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Variable interest entity notes | 133 | 276
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 3 [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Long-term debt | 0 | 0
Medium-term notes | 328 | 396
Investment agreements | 358 | 376
Total liabilities | 686 | 772
Gross | 921 | 811
Ceded recoverable (liability) | 47 | 45
Fair Value [Member] | Value Disclosed At Fair Value Not Recorded At Fair Value [Member] | Fair Value Inputs Level 3 [Member] | Variable Interest Entity Primary Beneficiary [Member] | Fair Value Measurements Nonrecurring [Member] |  |
Fair Value Off Balance Sheet Risks Disclosure Information [Line Items] |  |
Variable interest entity notes | $ 0 | $ 0

X
- Definition Represents the Company's balance sheet carrying amount of the financial guarantee insurance contracts ceded to third party reinsurers. The balance sheet carrying amount comprises the prepaid reinsurance premiums and reinsurance recoverable on paid and unpaid losses + References No definition available. + Details
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- Definition Represents the Company's balance sheet carrying amount of the financial guarantee insurance contract obligations with third parties. The gross balance sheet carrying amount comprises the unearned premium revenue and the loss and loss adjustment expense reserves balances + References No definition available. + Details
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- Definition The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. + References No definition available. + Details
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