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Segment Information - Reconciliation of Net Income (Loss) Attributable to AGL to Segment Adjusted Operating Income (Loss) (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2024 | Dec. 31, 2023 | Dec. 31, 2022
Segment Reporting Information [Line Items] |  |  |
Total revenues | $ 872 | $ 1,373 | $ 723
Total expenses | 446 | 733 | 536
Equity in earnings (losses) of investees | 62 | 28 | (39)
Less: Segment provision (benefit) for income taxes | 96 | (93) | 11
Less: Noncontrolling interests | 16 | 22 | 13
Net income (loss) attributable to Assured Guaranty Ltd. | 376 | 739 | 124
Bermuda ETA | 1 | 189 | 0
Subtotal |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 886 | 1,267 | 887
Total expenses | 447 | 735 | 540
Equity in earnings (losses) of investees | 62 | 28 | (39)
Less: Segment provision (benefit) for income taxes | 96 | (110) | 28
Less: Noncontrolling interests | 16 | 22 | 13
Net income (loss) attributable to Assured Guaranty Ltd. | 389 | 648 | 267
Realized gains (losses) on investments |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 9 | (14) | (56)
Net income (loss) attributable to Assured Guaranty Ltd. | 9 | (14) | (56)
Non-credit impairment-related unrealized fair value gains (losses) on credit derivatives |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 13 | 104 | (22)
Net income (loss) attributable to Assured Guaranty Ltd. | 14 | 106 | (18)
Fair value gains (losses) on CCS |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | (10) | (35) | 24
Net income (loss) attributable to Assured Guaranty Ltd. | (10) | (35) | 24
Foreign exchange gains (losses) on remeasurement of premiums receivable and loss and LAE reserves |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | (26) | 51 | (110)
Net income (loss) attributable to Assured Guaranty Ltd. | (26) | 51 | (110)
Tax effect |  |  |
Segment Reporting Information [Line Items] |  |  |
Less: Segment provision (benefit) for income taxes | 0 | (17) | 17
Net income (loss) attributable to Assured Guaranty Ltd. | 0 | (17) | 17
Operating segments |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 831 | 931 | 869
Total expenses | 295 | 513 | 378
Equity in earnings (losses) of investees | 104 | 87 | (51)
Less: Segment provision (benefit) for income taxes | 110 | (119) | 33
Less: Noncontrolling interests | 0 | 0 | 0
Net income (loss) attributable to Assured Guaranty Ltd. | 530 | 624 | 407
Operating segments | Insurance |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 821 | 855 | 757
Total expenses | 289 | 435 | 259
Equity in earnings (losses) of investees | 102 | 82 | (51)
Less: Segment provision (benefit) for income taxes | 109 | (119) | 34
Less: Noncontrolling interests | 0 | 0 | 0
Net income (loss) attributable to Assured Guaranty Ltd. | 525 | 621 | 413
Operating segments | Asset Management |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 10 | 76 | 112
Total expenses | 6 | 78 | 119
Equity in earnings (losses) of investees | 2 | 5 | 0
Less: Segment provision (benefit) for income taxes | 1 | 0 | (1)
Less: Noncontrolling interests | 0 | 0 | 0
Net income (loss) attributable to Assured Guaranty Ltd. | 5 | 3 | (6)
Corporate division |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 17 | 275 | 4
Total expenses | 169 | 216 | 143
Equity in earnings (losses) of investees | 5 | 0 | 0
Less: Segment provision (benefit) for income taxes | (12) | 14 | (5)
Less: Noncontrolling interests | 0 | 0 | 0
Net income (loss) attributable to Assured Guaranty Ltd. | (135) | 45 | (134)
Intersegment, other |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 38 |  |
Total expenses | (17) |  |
Equity in earnings (losses) of investees | (47) |  |
Less: Segment provision (benefit) for income taxes | (2) |  |
Less: Noncontrolling interests | 16 |  |
Net income (loss) attributable to Assured Guaranty Ltd. | (6) |  |
Intersegment, other | Insurance |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 10 | 10 | 9
Intersegment, other | Asset Management |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 2 | 27 | 34
Other |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues |  | 61 | 14
Total expenses |  | 6 | 19
Equity in earnings (losses) of investees |  | (59) | 12
Less: Segment provision (benefit) for income taxes |  | (5) | 0
Less: Noncontrolling interests |  | 22 | 13
Net income (loss) attributable to Assured Guaranty Ltd. |  | (21) | (6)
Reconciling item |  |  |
Segment Reporting Information [Line Items] |  |  |
Total expenses | $ (1) | $ (2) | $ (4)

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