Investment Securities - Rollforward of Fair Value Measurements by Level (Details) - Other long-term investments - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2025	Dec. 31, 2024
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	$ 1,262.7	$ 1,138.2
Net realized and unrealized gains	141.0	54.4
Purchases and contributions	202.2	111.5
Effect of Bamboo Transaction	250.0	0.0
Effect of Distinguished Transaction	(7.1)	0.0
Sales and distributions	(34.4)	(41.4)
Transfers in	0.0	0.0
Transfers out	0.0	0.0
Ending balance	$ 1,814.4	$ 1,262.7