v3.26.3
Fair Value Measurements (Tables)
 9 Months Ended
Sep. 30, 2026
Fair Value Disclosures [Abstract]  
Schedule of Financial Instruments Measured at Fair Value on a Recurring Basis
The following tables present the financial instruments measured at fair value on a recurring basis at September 30, 2026 and December 31, 2025:
September 30, 2026
AssetsLevel 1Level 2Level 3Total
Fixed maturity securities
U.S. Treasuries$336.3 $— $— $336.3 
Non-U.S. government— 38.6 — 38.6 
Corporate bonds— 1,697.9 — 1,697.9 
Residential mortgage-backed— 424.4 — 424.4 
Commercial mortgage-backed— 10.1 — 10.1 
Other asset-backed securities— 285.4 — 285.4 
Total fixed maturity securities336.3 2,456.4 — 2,792.7 
Short-term investments
U.S. Treasuries266.9 — — 266.9 
Corporate bonds— 1.4 — 1.4 
Other asset-backed securities— 0.4 — 0.4 
Total short-term investments266.9 1.8 — 268.7 
Other assets
Investments pending settlement19.5 — — 19.5 
Derivative assets— 0.3 — 0.3 
Total other assets19.5 0.3 — 19.8 
Total assets measured at fair value$622.7 $2,458.5 $— $3,081.2 
Liabilities
Investments pending settlement$(21.3)$— $— $(21.3)
Total other liabilities(21.3)— — (21.3)
Total liabilities measured at fair value$(21.3)$— $— $(21.3)
December 31, 2025
AssetsLevel 1Level 2Level 3Total
Fixed maturity securities
U.S. Treasuries$484.2 $— $— $484.2 
Agencies— 6.9 — 6.9 
Non-U.S. government— 47.2 — 47.2 
Corporate bonds— 1,652.2 — 1,652.2 
Residential mortgage-backed— 249.9 — 249.9 
Commercial mortgage-backed— 1.0 — 1.0 
Other asset-backed securities— 199.0 — 199.0 
Total fixed maturity securities484.2 2,156.2 — 2,640.4 
Short-term investments
U.S. Treasuries109.9 — — 109.9 
Corporate bonds— 1.0 — 1.0 
Other asset-backed securities— 0.4 — 0.4 
Total short-term investments109.9 1.4 — 111.3 
Other assets
Investments pending settlement4.8 — — 4.8 
Derivative assets— 2.4 — 2.4 
Total other assets4.8 2.4 — 7.2 
Total assets measured at fair value$598.9 $2,160.0 $— $2,758.9 
Liabilities
Other liabilities
Investments pending settlement$(6.6)$— $— $(6.6)
Derivative liabilities— (1.7)— (1.7)
Total other liabilities(6.6)(1.7)— (8.3)
Total liabilities measured at fair value$(6.6)$(1.7)$— $(8.3)
Schedule of Financial Instruments Based on Observable Inputs
The following table presents financial instruments for which the carrying value differs from the estimated fair values at September 30, 2026 and December 31, 2025. The fair values of the below financial instruments are based on observable inputs and are considered Level 2 measurements.
September 30, 2026December 31, 2025
Fair ValueCarrying ValueFair ValueCarrying Value
7.750% Subordinated notes due 2055
$414.5 $393.8 $431.0 $393.5 
4.875% Senior notes due 2030
314.6 327.0 327.7 326.4 
6.625% Fixed Rate Reset Junior Subordinated notes due 2041
— — 124.4 123.3