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Business Segments (Summary Of Company's Segment Results) (Detail) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019 | Dec. 31, 2019
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | $ 34 | $ 47 | $ 116 | $ 155 |
Net change in fair value of insured derivatives |  |  |  |  | 13 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 13 | 44 | (26) | 40 |
Net investment losses related to other-than-temporary impairments |  |  |  |  | (37) |
Net gains (losses) on extinguishment of debt |  |  | (1) |  | (1) |
Other net realized gains (losses) |  |  | 0 |  | 2 |
Revenues of consolidated VIEs |  | 24 | 82 | 89 | 80 |
Inter-segment revenues | [2] | 0 | 0 | 0 | 0 |
Total revenues |  | 71 | 172 | 179 | 252 |
Losses and loss adjustment |  | 48 | (13) | 427 | 89 |
Operating |  | 23 | 26 | 68 | 77 |
Interest |  | 43 | 50 | 135 | 154 |
Expenses of consolidated VIEs |  | 15 | 20 | 46 | 69 |
Inter-segment expenses | [2] | 0 | 0 | 0 | 0 |
Total expenses |  | 129 | 83 | 676 | 389 |
Income (loss) before income taxes |  | (58) | 89 | (497) | (137) |
Identifiable assets |  | 6,551 |  | 6,551 |  | $ 7,284
Operating Segments [Member] | U S Public Finance Insurance [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 21 | 30 | 78 | 106 |
Net change in fair value of insured derivatives |  |  |  |  | 0 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 23 | 78 | 30 | 135 |
Net investment losses related to other-than-temporary impairments |  |  |  |  | (37) |
Net gains (losses) on extinguishment of debt |  |  | 0 |  | 0 |
Other net realized gains (losses) |  |  | 0 |  | 1 |
Revenues of consolidated VIEs |  | 0 | 32 | 0 | 38 |
Inter-segment revenues | [2] | 7 | 7 | 21 | 22 |
Total revenues |  | 51 | 147 | 129 | 265 |
Losses and loss adjustment |  | 14 | (90) | 134 | (34) |
Operating |  | 3 | 4 | 8 | 8 |
Interest |  | 0 | 0 | 0 | 0 |
Expenses of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment expenses | [2] | 9 | 14 | 34 | 41 |
Total expenses |  | 26 | (72) | 176 | 15 |
Income (loss) before income taxes |  | 25 | 219 | (47) | 250 |
Identifiable assets |  | 3,777 |  | 3,777 |  |
Operating Segments [Member] | Corporate Operations [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 4 | 6 | 15 | 21 |
Net change in fair value of insured derivatives |  |  |  |  | 0 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | (6) | (20) | (62) | (71) |
Net investment losses related to other-than-temporary impairments |  |  |  |  | 0 |
Net gains (losses) on extinguishment of debt |  |  | (1) |  | (1) |
Other net realized gains (losses) |  |  | (1) |  | (2) |
Revenues of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment revenues | [2] | 16 | 15 | 51 | 48 |
Total revenues |  | 14 | (1) | 4 | (5) |
Losses and loss adjustment |  | 0 | 0 | 0 | 0 |
Operating |  | 16 | 15 | 50 | 53 |
Interest |  | 16 | 17 | 48 | 56 |
Expenses of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment expenses | [2] | 6 | 6 | 17 | 17 |
Total expenses |  | 38 | 38 | 115 | 126 |
Income (loss) before income taxes |  | (24) | (39) | (111) | (131) |
Identifiable assets |  | 1,031 |  | 1,031 |  |
Operating Segments [Member] | International And Structured Finance Insurance [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 9 | 11 | 23 | 28 |
Net change in fair value of insured derivatives |  |  |  |  | 13 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | (4) | (14) | 6 | (24) |
Net investment losses related to other-than-temporary impairments |  |  |  |  | 0 |
Net gains (losses) on extinguishment of debt |  |  | 0 |  | 0 |
Other net realized gains (losses) |  |  | 1 |  | 3 |
Revenues of consolidated VIEs |  | 24 | 50 | 89 | 41 |
Inter-segment revenues | [2] | (1) | 6 | 7 | 15 |
Total revenues |  | 28 | 54 | 125 | 76 |
Losses and loss adjustment |  | 34 | 77 | 293 | 123 |
Operating |  | 4 | 7 | 10 | 16 |
Interest |  | 27 | 33 | 87 | 98 |
Expenses of consolidated VIEs |  | 15 | 20 | 46 | 69 |
Inter-segment expenses | [2] | 7 | 8 | 28 | 26 |
Total expenses |  | 87 | 145 | 464 | 332 |
Income (loss) before income taxes |  | (59) | (91) | (339) | (256) |
Identifiable assets |  | 4,309 |  | 4,309 |  |
Intersegment Elimination [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 0 | 0 | 0 | 0 |
Net change in fair value of insured derivatives |  |  |  |  | 0 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 0 | 0 | 0 | 0 |
Net investment losses related to other-than-temporary impairments |  |  |  |  | 0 |
Net gains (losses) on extinguishment of debt |  |  | 0 |  | 0 |
Other net realized gains (losses) |  |  | 0 |  | 0 |
Revenues of consolidated VIEs |  | 0 | 0 | 0 | 1 |
Inter-segment revenues | [2] | (22) | (28) | (79) | (85) |
Total revenues |  | (22) | (28) | (79) | (84) |
Losses and loss adjustment |  | 0 | 0 | 0 | 0 |
Operating |  | 0 | 0 | 0 | 0 |
Interest |  | 0 | 0 | 0 | 0 |
Expenses of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment expenses | [2] | (22) | (28) | (79) | (84) |
Total expenses |  | (22) | (28) | (79) | (84) |
Income (loss) before income taxes |  | 0 | $ 0 | 0 | $ 0 |
Identifiable assets | [3] | $ (2,566) |  | $ (2,566) |  |
[1] | Represents the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements and other fees.
[2] | Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables.
[3] | Consists principally of intercompany reinsurance balances.

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