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Business Segments (Summary Of Company's Segment Results) (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019 | Dec. 31, 2019
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | $ 39 | $ 53 | $ 82 | $ 108 |
Net change in fair value of insured derivatives |  |  | (1) |  | 13 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 24 | (26) | (39) | (4) |
Net investment losses related to other-than-temporary impairments |  |  | (9) |  | (37) |
Other net realized gains (losses) |  |  | 1 |  | 2 |
Revenues of consolidated VIEs |  | 51 | 12 | 65 | (2) |
Inter-segment revenues | [2] | 0 | 0 | 0 | 0 |
Total revenues |  | 114 | 30 | 108 | 80 |
Losses and loss adjustment |  | 136 | 140 | 379 | 102 |
Operating |  | 25 | 21 | 45 | 51 |
Interest |  | 45 | 52 | 92 | 104 |
Expenses of consolidated VIEs |  | 14 | 24 | 31 | 49 |
Inter-segment expenses | [2] | 0 | 0 | 0 | 0 |
Total expenses |  | 220 | 237 | 547 | 306 |
Income (loss) before income taxes |  | (106) | (207) | (439) | (226) |
Identifiable assets |  | 6,613 |  | 6,613 |  | $ 7,284
Operating Segments [Member] | U S Public Finance Insurance [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 26 | 38 | 57 | 76 |
Net change in fair value of insured derivatives |  |  | 0 |  | 0 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 25 | 17 | 7 | 57 |
Net investment losses related to other-than-temporary impairments |  |  | (9) |  | (37) |
Other net realized gains (losses) |  |  | 0 |  | 1 |
Revenues of consolidated VIEs |  | 0 | 20 | 0 | 6 |
Inter-segment revenues | [2] | 8 | 8 | 14 | 15 |
Total revenues |  | 59 | 74 | 78 | 118 |
Losses and loss adjustment |  | 72 | 106 | 120 | 56 |
Operating |  | 3 | 2 | 5 | 4 |
Interest |  | 0 | 0 | 0 | 0 |
Expenses of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment expenses | [2] | 11 | 12 | 25 | 27 |
Total expenses |  | 86 | 120 | 150 | 87 |
Income (loss) before income taxes |  | (27) | (46) | (72) | 31 |
Identifiable assets |  | 3,868 |  | 3,868 |  |
Operating Segments [Member] | Corporate Operations [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 5 | 8 | 11 | 15 |
Net change in fair value of insured derivatives |  |  | 0 |  | 0 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 0 | (33) | (56) | (51) |
Net investment losses related to other-than-temporary impairments |  |  | 0 |  | 0 |
Other net realized gains (losses) |  |  | 0 |  | (1) |
Revenues of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment revenues | [2] | 17 | 14 | 35 | 33 |
Total revenues |  | 22 | (11) | (10) | (4) |
Losses and loss adjustment |  | 0 | 0 | 0 | 0 |
Operating |  | 19 | 16 | 34 | 38 |
Interest |  | 16 | 20 | 32 | 39 |
Expenses of consolidated VIEs |  | 0 | 0 | 0 | 0 |
Inter-segment expenses | [2] | 6 | 5 | 11 | 11 |
Total expenses |  | 41 | 41 | 77 | 88 |
Income (loss) before income taxes |  | (19) | (52) | (87) | (92) |
Identifiable assets |  | 1,021 |  | 1,021 |  |
Operating Segments [Member] | International And Structured Finance Insurance [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 8 | 7 | 14 | 17 |
Net change in fair value of insured derivatives |  |  | (1) |  | 13 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | (1) | (10) | 10 | (10) |
Net investment losses related to other-than-temporary impairments |  |  | 0 |  | 0 |
Other net realized gains (losses) |  |  | 1 |  | 2 |
Revenues of consolidated VIEs |  | 51 | (9) | 65 | (9) |
Inter-segment revenues | [2] | 3 | 6 | 8 | 9 |
Total revenues |  | 61 | (6) | 97 | 22 |
Losses and loss adjustment |  | 64 | 34 | 259 | 46 |
Operating |  | 3 | 3 | 6 | 9 |
Interest |  | 29 | 32 | 60 | 65 |
Expenses of consolidated VIEs |  | 14 | 24 | 31 | 49 |
Inter-segment expenses | [2] | 11 | 10 | 21 | 18 |
Total expenses |  | 121 | 103 | 377 | 187 |
Income (loss) before income taxes |  | (60) | (109) | (280) | (165) |
Identifiable assets |  | 4,077 |  | 4,077 |  |
Intersegment Elimination [Member] |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |
Revenues | [1] | 0 | 0 | 0 | 0 |
Net change in fair value of insured derivatives |  |  | 0 |  | 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 |  | 0 |
Other net realized gains (losses) |  |  | 0 |  | 0 |
Revenues of consolidated VIEs |  | 0 | 1 | 0 | 1 |
Inter-segment revenues | [2] | (28) | (28) | (57) | (57) |
Total revenues |  | (28) | (27) | (57) | (56) |
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] | (28) | (27) | (57) | (56) |
Total expenses |  | (28) | (27) | (57) | (56) |
Income (loss) before income taxes |  | 0 | $ 0 | 0 | $ 0 |
Identifiable assets | [3] | $ (2,353) |  | $ (2,353) |  |
[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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