Goodwill and Intangible Assets - Goodwill (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Goodwill [Line Items]
Gross value	$ 822.2	$ 822.4
Less accumulated impairment	253.3	253.3
Net	568.9	569.1
KGS
Goodwill [Line Items]
Gross value	683.6	683.6
Less accumulated impairment	239.5	239.5
Net	444.1	444.1
US
Goodwill [Line Items]
Gross value	138.6	138.8
Less accumulated impairment	13.8	13.8
Net	$ 124.8	$ 125.0