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Investments (Tables) | 9 Months Ended
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Sep. 30, 2024
Investments, Debt and Equity Securities [Abstract] |
Schedule of Available-for-sale Fixed Maturities Reconciliation | The amortized cost and fair value of available-for-sale fixed maturities were as follows:
|  | September 30, 2024 |
|  |  |  |  |  |  |  | Amortized Cost, |  |  |  |  |  |  |  |  |  |
|  |  |  |  | Allowance |  |  | Net of Allowance |  |  | Gross |  |  | Gross |  |  |  |
|  | Amortized |  |  | for Credit |  |  | for Credit |  |  | Unrealized |  |  | Unrealized |  |  |  |
(in millions) |  | Cost |  |  | Losses |  |  | Losses |  |  | Gains |  |  | Losses |  |  | Fair Value |
U.S. Treasury and government agencies |  | $ | 616.8 |  |  | $ | — |  |  | $ | 616.8 |  |  | $ | 4.0 |  |  | $ | 44.0 |  |  | $ | 576.8 |
Foreign governments |  |  | 1.7 |  |  |  | — |  |  |  | 1.7 |  |  |  | 0.1 |  |  |  | — |  |  |  | 1.8 |
Municipals |  |  | 1,135.0 |  |  |  | — |  |  |  | 1,135.0 |  |  |  | 4.3 |  |  |  | 90.0 |  |  |  | 1,049.3 |
Corporates |  |  | 4,047.3 |  |  |  | (0.6 | ) |  |  | 4,046.7 |  |  |  | 46.1 |  |  |  | 118.9 |  |  |  | 3,973.9 |
Residential mortgage-backed |  |  | 1,813.2 |  |  |  | — |  |  |  | 1,813.2 |  |  |  | 20.7 |  |  |  | 105.1 |  |  |  | 1,728.8 |
Commercial mortgage-backed |  |  | 621.9 |  |  |  | — |  |  |  | 621.9 |  |  |  | 0.7 |  |  |  | 36.4 |  |  |  | 586.2 |
Other asset-backed |  |  | 701.2 |  |  |  | — |  |  |  | 701.2 |  |  |  | 4.2 |  |  |  | 2.2 |  |  |  | 703.2 |
Total fixed maturities |  | $ | 8,937.1 |  |  | $ | (0.6 | ) |  | $ | 8,936.5 |  |  | $ | 80.1 |  |  | $ | 396.6 |  |  | $ | 8,620.0 |
|  | December 31, 2023 |
|  |  |  |  |  |  |  | Amortized Cost, |  |  |  |  |  |  |  |  |  |
|  |  |  |  | Allowance |  |  | Net of Allowance |  |  | Gross |  |  | Gross |  |  |  |
|  | Amortized |  |  | for Credit |  |  | for Credit |  |  | Unrealized |  |  | Unrealized |  |  |  |
(in millions) |  | Cost |  |  | Losses |  |  | Losses |  |  | Gains |  |  | Losses |  |  | Fair Value |
U.S. Treasury and government agencies |  | $ | 512.9 |  |  | $ | — |  |  | $ | 512.9 |  |  | $ | 1.4 |  |  | $ | 51.7 |  |  | $ | 462.6 |
Foreign governments |  |  | 2.2 |  |  |  | — |  |  |  | 2.2 |  |  |  | — |  |  |  | — |  |  |  | 2.2 |
Municipals |  |  | 1,309.3 |  |  |  | — |  |  |  | 1,309.3 |  |  |  | 5.5 |  |  |  | 129.6 |  |  |  | 1,185.2 |
Corporates |  |  | 4,053.8 |  |  |  | (1.9 | ) |  |  | 4,051.9 |  |  |  | 22.9 |  |  |  | 225.1 |  |  |  | 3,849.7 |
Residential mortgage-backed |  |  | 1,435.6 |  |  |  | — |  |  |  | 1,435.6 |  |  |  | 5.5 |  |  |  | 130.2 |  |  |  | 1,310.9 |
Commercial mortgage-backed |  |  | 890.3 |  |  |  | — |  |  |  | 890.3 |  |  |  | 0.1 |  |  |  | 72.2 |  |  |  | 818.2 |
Other asset-backed |  |  | 371.7 |  |  |  | — |  |  |  | 371.7 |  |  |  | 0.7 |  |  |  | 15.9 |  |  |  | 356.5 |
Total fixed maturities |  | $ | 8,575.8 |  |  | $ | (1.9 | ) |  | $ | 8,573.9 |  |  | $ | 36.1 |  |  | $ | 624.7 |  |  | $ | 7,985.3 |
Investments Classified by Contractual Maturity Date | The amortized cost and fair value by maturity periods for fixed maturities are shown in the following table. Actual maturities may differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties, or the Company may have the right to put or sell the obligations back to the issuers.
|  | September 30, 2024 |
|  | Amortized Cost, Net |  |  |  |
|  | of Allowance for |  |  | Fair |
(in millions) |  | Credit Losses |  |  | Value |
Due in one year or less |  | $ | 369.6 |  |  | $ | 367.8 |
Due after one year through five years |  |  | 2,623.2 |  |  |  | 2,594.7 |
Due after five years through ten years |  |  | 2,552.5 |  |  |  | 2,407.8 |
Due after ten years |  |  | 254.9 |  |  |  | 231.5 |
|  |  | 5,800.2 |  |  |  | 5,601.8 |
Mortgage-backed and other asset-backed securities |  |  | 3,136.3 |  |  |  | 3,018.2 |
Total fixed maturities |  | $ | 8,936.5 |  |  | $ | 8,620.0 |
Schedule of Unrealized Loss on Investments | The following tables provide information about the Company’s available-for-sale fixed maturity securities that were in an unrealized loss position at September 30, 2024 and December 31, 2023, including the length of time the securities have been in an unrealized loss position:
|  | September 30, 2024 |
|  | 12 months or less |  |  | Greater than 12 months |  |  | Total |
|  | Gross |  |  |  |  |  | Gross |  |  |  |  |  | Gross |  |  |  |
|  | Unrealized |  |  | Fair |  |  | Unrealized |  |  | Fair |  |  | Unrealized |  |  | Fair |
(in millions) |  | Losses |  |  | Value |  |  | Losses |  |  | Value |  |  | Losses |  |  | Value |
Investment grade: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury and government agencies |  | $ | 0.3 |  |  | $ | 106.0 |  |  | $ | 43.7 |  |  | $ | 330.2 |  |  | $ | 44.0 |  |  | $ | 436.2 |
Municipals |  |  | 0.2 |  |  |  | 39.8 |  |  |  | 89.8 |  |  |  | 848.0 |  |  |  | 90.0 |  |  |  | 887.8 |
Corporates |  |  | 0.6 |  |  |  | 347.4 |  |  |  | 112.6 |  |  |  | 2,005.6 |  |  |  | 113.2 |  |  |  | 2,353.0 |
Residential mortgage-backed |  |  | 0.1 |  |  |  | 78.1 |  |  |  | 105.0 |  |  |  | 808.1 |  |  |  | 105.1 |  |  |  | 886.2 |
Commercial mortgage-backed |  |  | — |  |  |  | — |  |  |  | 36.4 |  |  |  | 545.4 |  |  |  | 36.4 |  |  |  | 545.4 |
Other asset-backed |  |  | 0.2 |  |  |  | 60.8 |  |  |  | 2.0 |  |  |  | 126.1 |  |  |  | 2.2 |  |  |  | 186.9 |
Total investment grade |  |  | 1.4 |  |  |  | 632.1 |  |  |  | 389.5 |  |  |  | 4,663.4 |  |  |  | 390.9 |  |  |  | 5,295.5 |
Below investment grade: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporates |  |  | 0.9 |  |  |  | 61.7 |  |  |  | 4.8 |  |  |  | 57.1 |  |  |  | 5.7 |  |  |  | 118.8 |
Commercial mortgage-backed |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.9 |  |  |  | — |  |  |  | 0.9 |
Total below investment grade |  |  | 0.9 |  |  |  | 61.7 |  |  |  | 4.8 |  |  |  | 58.0 |  |  |  | 5.7 |  |  |  | 119.7 |
Total fixed maturities |  | $ | 2.3 |  |  | $ | 693.8 |  |  | $ | 394.3 |  |  | $ | 4,721.4 |  |  | $ | 396.6 |  |  | $ | 5,415.2 |
|  | December 31, 2023 |
|  | 12 months or less |  |  | Greater than 12 months |  |  | Total |
|  | Gross |  |  |  |  |  | Gross |  |  |  |  |  | Gross |  |  |  |
|  | Unrealized |  |  | Fair |  |  | Unrealized |  |  | Fair |  |  | Unrealized |  |  | Fair |
(in millions) |  | Losses |  |  | Value |  |  | Losses |  |  | Value |  |  | Losses |  |  | Value |
Investment grade: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
U.S. Treasury and government agencies |  | $ | 0.6 |  |  | $ | 62.2 |  |  | $ | 51.1 |  |  | $ | 331.0 |  |  | $ | 51.7 |  |  | $ | 393.2 |
Foreign governments |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 2.0 |  |  |  | — |  |  |  | 2.0 |
Municipals |  |  | 2.5 |  |  |  | 72.5 |  |  |  | 127.1 |  |  |  | 935.2 |  |  |  | 129.6 |  |  |  | 1,007.7 |
Corporates |  |  | 1.3 |  |  |  | 159.9 |  |  |  | 214.9 |  |  |  | 2,870.2 |  |  |  | 216.2 |  |  |  | 3,030.1 |
Residential mortgage-backed |  |  | 1.2 |  |  |  | 139.3 |  |  |  | 129.0 |  |  |  | 865.4 |  |  |  | 130.2 |  |  |  | 1,004.7 |
Commercial mortgage-backed |  |  | 0.2 |  |  |  | 14.0 |  |  |  | 72.0 |  |  |  | 770.0 |  |  |  | 72.2 |  |  |  | 784.0 |
Other asset-backed |  |  | 0.1 |  |  |  | 28.1 |  |  |  | 15.8 |  |  |  | 260.2 |  |  |  | 15.9 |  |  |  | 288.3 |
Total investment grade |  |  | 5.9 |  |  |  | 476.0 |  |  |  | 609.9 |  |  |  | 6,034.0 |  |  |  | 615.8 |  |  |  | 6,510.0 |
Below investment grade: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporates |  |  | 2.5 |  |  |  | 33.8 |  |  |  | 6.4 |  |  |  | 66.2 |  |  |  | 8.9 |  |  |  | 100.0 |
Commercial mortgage-backed |  |  | — |  |  |  | — |  |  |  | — |  |  |  | 0.9 |  |  |  | — |  |  |  | 0.9 |
Total below investment grade |  |  | 2.5 |  |  |  | 33.8 |  |  |  | 6.4 |  |  |  | 67.1 |  |  |  | 8.9 |  |  |  | 100.9 |
Total fixed maturities |  | $ | 8.4 |  |  | $ | 509.8 |  |  | $ | 616.3 |  |  | $ | 6,101.1 |  |  | $ | 624.7 |  |  | $ | 6,610.9 |
Schedule of Realized Gain (Loss) | The proceeds from sales of available-for-sale fixed maturities and gross realized gains and gross realized losses on those sales were as follows:
|  | Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
|  | 2024 |  |  | 2023 |  |  | 2024 |  |  | 2023 |
(in millions) |  |  |  |  |  |  |  |  |  |  |  |
Proceeds from sales |  | $ | 479.5 |  |  | $ | 16.9 |  |  | $ | 1,145.9 |  |  | $ | 103.5 |
Gross gains |  |  | 0.5 |  |  |  | — |  |  |  | 2.4 |  |  |  | 0.9 |
Gross losses |  |  | 25.8 |  |  |  | 1.3 |  |  |  | 60.1 |  |  |  | 3.3 |
Schedule of Allowance for Credit Losses | The following table provides a rollforward of the allowance for credit losses on mortgage loans:
| Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
(in millions) | 2024 |  |  | 2023 |  |  | 2024 |  |  | 2023 |
Allowance for credit losses as of the beginning of the period | $ | 8.6 |  |  | $ | 8.5 |  |  | $ | 10.0 |  |  | $ | 3.2 |
Reductions for writedowns |  | — |  |  |  | — |  |  |  | (3.0 | ) |  |  | — |
Reductions for disposals |  | (1.3 | ) |  |  | — |  |  |  | (1.6 | ) |  |  | — |
Additional credit losses on investments for which an allowance was previously recognized |  | 0.2 |  |  |  | — |  |  |  | 2.1 |  |  |  | 5.4 |
Recoveries |  | — |  |  |  | — |  |  |  | — |  |  |  | (0.1 | )
Allowance for credit losses as of the end of the period | $ | 7.5 |  |  | $ | 8.5 |  |  | $ | 7.5 |  |  | $ | 8.5 |
Schedule of Pre-tax Net Realized and Unrealized Gains (Losses) on Equity Securities | The following table provides pre-tax net unrealized gains (losses) on equity securities. There were no realized gains or losses from sales of equities for the three or nine months ended September 30, 2024.
| Three Months Ended September 30, |  |  | Nine Months Ended September 30, |
(in millions) | 2024 |  |  | 2023 |  |  | 2024 |  |  | 2023 |
Net gains (losses) recognized during the period | $ | 11.7 |  |  | $ | (5.2 | ) |  | $ | 19.3 |  |  | $ | (13.4 | )
Less: net losses recognized on equity securities sold during the period |  | — |  |  |  | (11.9 | ) |  |  | — |  |  |  | (11.9 | )
Net unrealized gains (losses) recognized during the period on equity securities still held | $ | 11.7 |  |  | $ | 6.7 |  |  | $ | 19.3 |  |  | $ | (1.5 | )

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