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Stockholders' Equity - Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions | 3 Months Ended
--- | ---
Mar. 31, 2025 | Mar. 31, 2024
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss), pre-tax | $ 533.3 | $ 153.2
Other comprehensive income (loss), tax | (101.2) | (65.8)
Other comprehensive income (loss) | 432.1 | 87.4
Net unrealized gains (losses) on available-for-sale securities including NCI |  |
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss) before reclassifications, pre-tax | 666.8 | (507.7)
Adjustments for assumed changes in amortization patterns, pre-tax | (0.4) | (0.2)
Adjustments for assumed changes in policyholder liabilities, pre-tax | 18.3 | 8.2
Other comprehensive income (loss), pre-tax | 747.2 | (456.2)
Other comprehensive income (loss) before reclassifications, tax | (140.9) | 108.3
Reclassification from accumulated other comprehensive income, tax | (13.1) | (9.0)
Adjustments for assumed changes in amortization patterns, tax | 0.1 |
Adjustments for assumed changes in policyholder liabilities, tax | (3.9) | (1.7)
Other comprehensive income (loss), tax | (157.8) | 97.6
Other comprehensive income (loss) before reclassifications, after-tax | 525.9 | (399.4)
Reclassification from accumulated other comprehensive income, after-tax | 49.4 | 34.5
Adjustments for assumed changes in amortization patterns, after-tax | (0.3) | (0.2)
Adjustments for assumed changes in policyholder liabilities, after-tax | 14.4 | 6.5
Other comprehensive income (loss) | 589.4 | (358.6)
Net unrealized gains (losses) on available-for-sale securities including NCI | Net realized capital gains (losses) |  |
Other Comprehensive Income (Loss) |  |
Reclassification from accumulated other comprehensive income, pre-tax | 62.5 | 43.5
Net unrealized gains (losses) on derivative instruments including NCI |  |
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss) before reclassifications, pre-tax | 18.5 | 23.1
Reclassification from accumulated other comprehensive income, pre-tax | (0.6) | (0.9)
Adjustments for assumed changes in amortization patterns, pre-tax |  | (0.1)
Other comprehensive income (loss), pre-tax | 17.9 | 22.1
Other comprehensive income (loss) before reclassifications, tax | (3.9) | (4.8)
Reclassification from accumulated other comprehensive income, tax | 0.1 | 0.2
Other comprehensive income (loss), tax | (3.8) | (4.6)
Other comprehensive income (loss) before reclassifications, after-tax | 14.6 | 18.3
Reclassification from accumulated other comprehensive income, after-tax | (0.5) | (0.7)
Adjustments for assumed changes in amortization patterns, after-tax |  | (0.1)
Other comprehensive income (loss) | 14.1 | 17.5
Liability for future policy benefits discount rate remeasurement gain (loss) |  |
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss), pre-tax | (312.4) | 710.2
Other comprehensive income (loss), tax | 62.6 | (155.5)
Other comprehensive income (loss) | (249.8) | 554.7
Market risk benefit nonperformance risk remeasurement gain(loss) |  |
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss), pre-tax | 2.7 | (11.0)
Other comprehensive income (loss), tax | (0.6) | 2.3
Other comprehensive income (loss) | 2.1 | (8.7)
Foreign currency translation adjustment including NCI |  |
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss), pre-tax | 74.1 | (116.7)
Other comprehensive income (loss), tax | (0.7) | (4.3)
Other comprehensive income (loss) | 73.4 | (121.0)
Unrecognized postretirement benefit obligation including NCI |  |
Other Comprehensive Income (Loss) |  |
Other comprehensive income (loss), pre-tax | 3.8 | 4.8
Reclassification from accumulated other comprehensive income, tax | (0.9) | (1.3)
Other comprehensive income (loss), tax | (0.9) | (1.3)
Reclassification from accumulated other comprehensive income, after-tax | 2.9 | 3.5
Other comprehensive income (loss) | 2.9 | 3.5
Unrecognized postretirement benefit obligation including NCI | Operating expense |  |
Other Comprehensive Income (Loss) |  |
Reclassification from accumulated other comprehensive income, pre-tax | $ 3.8 | $ 4.8

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