Statutory Financial Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Traditional U.S. Life Insurance Subsidiaries
Statutory Accounting Practices
Statutory Net Income (Loss)	$ 634.0	$ 1,322.4	$ 1,329.9
Statutory Combined Net Gain (Loss) from Operations	652.5	1,337.0	1,351.5
Statutory Combined Capital and Surplus	3,770.6	3,909.7
Captive Reinsurers
Statutory Accounting Practices
Statutory Net Income (Loss)	52.5	662.2	(318.3)
Statutory Combined Net Gain (Loss) from Operations	75.5	660.3	$ (279.4)
Statutory Combined Capital and Surplus	$ 2,003.3	$ 1,931.6