Segment Information - Revenue and Long-Lived Assets by Geographic Area (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2025	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2025	Dec. 31, 2024	Dec. 31, 2023
Revenue from external customers and Long-lived assets, net
Revenues	$ 7,769.2	$ 8,053.0	$ 8,032.5	$ 7,953.8	$ 8,077.6	$ 7,929.5	$ 8,065.0	$ 7,792.7	$ 31,808.5	$ 31,864.8	$ 30,916.5
Long-lived assets, net	5,261.4				4,975.0				5,261.4	4,975.0
U.S.
Revenue from external customers and Long-lived assets, net
Revenues									19,578.8	19,124.7	18,575.6
Long-lived assets, net	3,751.1				3,561.0				3,751.1	3,561.0
U.K.
Revenue from external customers and Long-lived assets, net
Revenues									8,334.4	9,322.0	9,240.4
Long-lived assets, net	1,029.4				975.5				1,029.4	975.5
Other International
Revenue from external customers and Long-lived assets, net
Revenues									3,895.3	3,418.1	$ 3,100.5
Long-lived assets, net	$ 480.9				$ 438.5				$ 480.9	$ 438.5