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Business Segments (Summary Of Company's Segment Results) (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014 | Dec. 31, 2013
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Revenues |  | $ 530 | [1] | $ 616 | [2] | $ 644 | [2]
Net change in fair value of insured derivatives |  | 129 |  | 459 |  | 232 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 63 |  | 78 |  | 69 |
Net investment losses related to other-than-temporary impairments |  | (13) |  | (15) |  |  |
Net gains (losses) on extinguishment of debt |  | (1) |  | 3 |  | 60 |
Other net realized gains (losses) |  | 17 |  | 28 |  | (29) |
Revenues of consolidated VIEs |  | 128 |  | 101 |  | 233 |
Inter-segment revenues |  | 0 | [3] | 0 | [4] | 0 | [4]
Total revenues |  | 853 |  | 1,270 |  | 1,209 |
Losses and loss adjustment |  | 123 |  | 133 |  | 117 |
Operating |  | 190 |  | 239 |  | 384 |
Interest |  | 199 |  | 210 |  | 236 |
Expenses of consolidated VIEs |  | 52 |  | 47 |  | 56 |
Inter-segment expenses |  | 0 | [3] | 0 | [4] | 0 | [4]
Total expenses |  | 564 |  | 629 |  | 793 |
Income (loss) before income taxes |  | 289 |  | 641 |  | 416 |
Provision (benefit) for income taxes |  | 109 |  | 72 |  | 166 |
Net income (loss) |  | 180 |  | 569 |  | 250 |
Identifiable assets |  | 14,855 |  | 16,284 |  | 16,953 |
U S Public Finance Insurance [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Losses and loss adjustment |  | 5 |  | (10) |  | 105 |
Operating Segments [Member] | U S Public Finance Insurance [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Revenues |  | 389 | [1] | 373 | [2] | 425 | [2]
Net change in fair value of insured derivatives |  |  |  | 1 |  | 3 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 14 |  | 26 |  | 29 |
Net investment losses related to other-than-temporary impairments |  | (10) |  | (15) |  |  |
Other net realized gains (losses) |  | (4) |  | 14 |  | (29) |
Inter-segment revenues |  | 34 | [3] | 44 | [4] | 90 | [4]
Total revenues |  | 423 |  | 443 |  | 518 |
Losses and loss adjustment |  | 5 |  | (10) |  | 105 |
Operating |  | 38 |  | 38 |  | 66 |
Inter-segment expenses |  | 89 | [3] | 78 | [4] | 96 | [4]
Total expenses |  | 132 |  | 106 |  | 267 |
Income (loss) before income taxes |  | 291 |  | 337 |  | 251 |
Provision (benefit) for income taxes |  | 100 |  | 115 |  | 82 |
Net income (loss) |  | 191 |  | 222 |  | 169 |
Identifiable assets |  | 5,265 |  | 5,887 |  | 6,056 |
Operating Segments [Member] | Corporate Operations [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Revenues |  | 27 | [1] | 42 | [2] | 55 | [2]
Net gains (losses) on financial instruments at fair value and foreign exchange |  | 58 |  | 55 |  | 15 |
Net investment losses related to other-than-temporary impairments |  | (3) |  |  |  |  |
Net gains (losses) on extinguishment of debt |  | (1) |  | 3 |  | 22 |
Other net realized gains (losses) |  | 21 |  | 2 |  |  |
Revenues of consolidated VIEs |  |  |  |  |  | (14) |
Inter-segment revenues |  | 67 | [3] | 46 | [4] | 85 | [4]
Total revenues |  | 169 |  | 148 |  | 163 |
Operating |  | 79 |  | 87 |  | 157 |
Interest |  | 97 |  | 101 |  | 124 |
Inter-segment expenses |  | 7 | [3] | 15 | [4] | 7 | [4]
Total expenses |  | 183 |  | 203 |  | 288 |
Income (loss) before income taxes |  | (14) |  | (55) |  | (125) |
Provision (benefit) for income taxes |  | 7 |  | (173) |  | (15) |
Net income (loss) |  | (21) |  | 118 |  | (110) |
Identifiable assets |  | 2,606 |  | 2,846 |  | 2,641 |
Operating Segments [Member] | International And Structured Finance Insurance [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Revenues |  | 114 | [1] | 189 | [2] | 148 | [2]
Net change in fair value of insured derivatives |  | 129 |  | 458 |  | 229 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  | (9) |  |  |  | 24 |
Other net realized gains (losses) |  |  |  | 12 |  |  |
Revenues of consolidated VIEs |  | 128 |  | 105 |  | 237 |
Inter-segment revenues |  | 63 | [3] | 55 | [4] | 78 | [4]
Total revenues |  | 425 |  | 819 |  | 716 |
Losses and loss adjustment |  | 118 |  | 143 |  | 12 |
Operating |  | 73 |  | 72 |  | 108 |
Interest |  | 102 |  | 109 |  | 112 |
Expenses of consolidated VIEs |  | 52 |  | 47 |  | 50 |
Inter-segment expenses |  | 64 | [3] | 64 | [4] | 136 | [4]
Total expenses |  | 409 |  | 435 |  | 418 |
Income (loss) before income taxes |  | 16 |  | 384 |  | 298 |
Provision (benefit) for income taxes |  | 3 |  | 134 |  | 101 |
Net income (loss) |  | 13 |  | 250 |  | 197 |
Identifiable assets |  | 9,882 |  | 10,086 |  | 11,687 |
Operating Segments [Member] | Advisory Services [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Revenues | [2] |  |  | 12 |  | 16 |
Net gains (losses) on financial instruments at fair value and foreign exchange |  |  |  | (3) |  | 1 |
Revenues of consolidated VIEs |  |  |  | (8) |  |  |
Inter-segment revenues | [4] |  |  | 22 |  | 26 |
Total revenues |  |  |  | 23 |  | 43 |
Operating |  |  |  | 42 |  | 53 |
Inter-segment expenses | [4] |  |  | 6 |  | 7 |
Total expenses |  |  |  | 48 |  | 60 |
Income (loss) before income taxes |  |  |  | (25) |  | (17) |
Provision (benefit) for income taxes |  |  |  | (6) |  | (5) |
Net income (loss) |  |  |  | (19) |  | (12) |
Identifiable assets |  |  |  | 793 |  | 44 |
Operating Segments [Member] | Conduit [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Revenues of consolidated VIEs |  |  |  | 4 |  | 10 |
Inter-segment revenues | [4] |  |  | (1) |  | (9) |
Total revenues |  |  |  | 3 |  | 1 |
Expenses of consolidated VIEs |  |  |  |  |  | 6 |
Inter-segment expenses | [4] |  |  | 9 |  | 26 |
Total expenses |  |  |  | 9 |  | 32 |
Income (loss) before income taxes |  |  |  | (6) |  | (31) |
Provision (benefit) for income taxes |  |  |  |  |  | (10) |
Net income (loss) |  |  |  | (6) |  | (21) |
Identifiable assets |  |  |  | 0 |  | 177 |
Intersegment Elimination [Member] |  |  |  |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |  |  |  |
Net gains (losses) on extinguishment of debt | [5] |  |  |  |  | 38 |
Inter-segment revenues |  | (164) | [3] | (166) | [4] | (270) | [4]
Total revenues |  | (164) |  | (166) |  | (232) |
Inter-segment expenses |  | (160) | [3] | (172) | [4] | (272) | [4]
Total expenses |  | (160) |  | (172) |  | (272) |
Income (loss) before income taxes |  | (4) |  | 6 |  | 40 |
Provision (benefit) for income taxes |  | (1) |  | 2 |  | 13 |
Net income (loss) |  | (3) |  | 4 |  | 27 |
Identifiable assets |  | $ (2,898) | [6] | $ (3,328) | [7] | $ (3,652) | [7]
[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 the sum of third-party financial guarantee net premiums earned, net investment income, insurance-related fees and reimbursements, investment management fees and other fees.
[3] | Represents intercompany premium income and expense and intercompany interest income and expense pertaining to intercompany receivables and payables.
[4] | Represents intercompany premium income and expense, intercompany asset management fees and expenses and intercompany interest income and expense pertaining to intercompany receivables and payables and intercompany loans.
[5] | Represents the gain on the debt received as consideration in connection with the settlement with Bank of America.
[6] | Consists of intercompany deferred income taxes, reinsurance balances and repurchase agreements.
[7] | Consists of intercompany reinsurance balances, repurchase agreements and deferred income taxes.

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