Revenues - Disaggregation of Revenues by Geography (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 1,328.7	$ 1,259.0	$ 2,623.7	$ 2,492.4
United States [Member]
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	937.4	894.6	1,860.4	1,773.0
United Kingdom [Member]
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	145.4	155.2	295.6	305.5
Europe (excluding United Kingdom), Middle East and Africa [Member]
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	98.1	85.9	187.6	155.7
Asia-Pacific and Japan [Member]
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	69.4	56.4	130.8	125.4
Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	54.2	45.3	104.6	93.3
Americas, excluding United States and Canada [Member]
Disaggregation Of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ 24.2	$ 21.6	$ 44.7	$ 39.5