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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, 2023 | Dec. 31, 2022 | Dec. 31, 2021
Segment Reporting Information [Line Items] |  |  |
Total revenues | $ 1,373 | $ 723 | $ 848
Total expenses | 733 | 536 | 465
Equity in earnings (losses) of investees | 28 | (39) | 94
Less: Segment provision (benefit) for income taxes | (93) | 11 | 58
Less: Noncontrolling interests | 22 | 13 | 30
Total consolidated | 739 | 124 | 389
Bermuda ETA | (189) | 0 | 0
Subtotal |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 1,267 | 887 | 960
Total expenses | 735 | 540 | 479
Equity in earnings (losses) of investees | 28 | (39) | 94
Less: Segment provision (benefit) for income taxes | (110) | 28 | 75
Less: Noncontrolling interests | 22 | 13 | 30
Total consolidated | 648 | 267 | 470
Operating Segments |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 931 | 869 | 816
Total expenses | 513 | 378 | 141
Equity in earnings (losses) of investees | 87 | (51) | 144
Less: Segment provision (benefit) for income taxes | (119) | 33 | 116
Less: Noncontrolling interests | 0 | 0 | 0
Total consolidated | 624 | 407 | 703
Operating Segments | Insurance |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 855 | 757 | 733
Total expenses | 435 | 259 | 33
Equity in earnings (losses) of investees | 82 | (51) | 144
Less: Segment provision (benefit) for income taxes | (119) | 34 | 122
Less: Noncontrolling interests | 0 | 0 | 0
Total consolidated | 621 | 413 | 722
Operating Segments | Asset Management |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 76 | 112 | 83
Total expenses | 78 | 119 | 108
Equity in earnings (losses) of investees | 5 | 0 | 0
Less: Segment provision (benefit) for income taxes | 0 | (1) | (6)
Less: Noncontrolling interests | 0 | 0 | 0
Total consolidated | 3 | (6) | (19)
Corporate division |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 275 | 4 | 2
Total expenses | 216 | 143 | 312
Equity in earnings (losses) of investees | 0 | 0 | 0
Less: Segment provision (benefit) for income taxes | 14 | (5) | (47)
Less: Noncontrolling interests | 0 | 0 | 0
Total consolidated | 45 | (134) | (263)
Other Operating Segments And Intersegment Eliminations |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 61 | 14 | 142
Total expenses | 6 | 19 | 26
Equity in earnings (losses) of investees | (59) | 12 | (50)
Less: Segment provision (benefit) for income taxes | (5) | 0 | 6
Less: Noncontrolling interests | 22 | 13 | 30
Total consolidated | (21) | (6) | 30
Segment Reconciling Items |  |  |
Segment Reporting Information [Line Items] |  |  |
Total expenses |  | (4) | (14)
Segment Reconciling Items | Realized gains (losses) on investments |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | (14) | (56) | 15
Total consolidated | (14) | (56) | 15
Segment Reconciling Items | Non-credit impairment-related unrealized fair value gains (losses) on credit derivatives |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 104 | (22) | (78)
Total expenses | (2) |  |
Total consolidated | 106 | (18) | (64)
Segment Reconciling Items | Fair value gains (losses) on CCS |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | (35) | 24 | (28)
Total consolidated | (35) | 24 | (28)
Segment Reconciling Items | Foreign exchange gains (losses) on remeasurement of premiums receivable and loss and LAE reserves |  |  |
Segment Reporting Information [Line Items] |  |  |
Total revenues | 51 | (110) | (21)
Total consolidated | 51 | (110) | (21)
Segment Reconciling Items | Provision (Benefit) for Income Taxes (1) |  |  |
Segment Reporting Information [Line Items] |  |  |
Less: Segment provision (benefit) for income taxes | (17) | 17 | 17
Total consolidated | $ (17) | $ 17 | $ 17

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