Senior Notes and Long-Term Debt - Senior Notes (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024	Nov. 19, 2025
Debt Instrument [Line Items]
Senior Notes	$ 3,351.5	$ 2,769.7
Senior Notes | Interest Rate Swaps
Debt Instrument [Line Items]
Change in unrealized gain (loss) on hedged item in fair value hedge	$ (142.2)	(224.2)
Fixed Rate Due May 2027
Debt Instrument [Line Items]
Interest rate	4.00%
Senior Notes	$ 999.0	998.3
Fixed Rate Due Aug. 2028
Debt Instrument [Line Items]
Interest rate	3.65%
Senior Notes	$ 493.5	479.6
Fixed Rate Due May 2029
Debt Instrument [Line Items]
Interest rate	3.15%
Senior Notes	$ 483.1	465.3
Fixed Rate Due May 2030
Debt Instrument [Line Items]
Interest rate	1.95%
Senior Notes	$ 879.8	826.5
Fixed Rate Due November 2030
Debt Instrument [Line Items]
Interest rate	4.15%		4.15%
Senior Notes	$ 496.1	$ 0.0