Goodwill - Schedule of Changes in Carrying Amounts of Goodwill (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Line Items]
Goodwill	$ 604.1	$ 602.7	$ 586.1
Accumulated impairment losses	(59.5)	(59.5)	(59.5)
Total	544.6	543.2	526.6
Acquisitions	1.0	16.3
Foreign currency translation	0.4	0.3
Commercial
Goodwill [Line Items]
Goodwill	388.1	387.0	377.1
Total	388.1	387.0	377.1
Acquisitions	1.0	10.1
Foreign currency translation	0.1	(0.2)
Aviation
Goodwill [Line Items]
Goodwill	216.0	215.7	209.0
Accumulated impairment losses	(59.5)	(59.5)	(59.5)
Total	156.5	156.2	$ 149.5
Acquisitions		6.2
Foreign currency translation	$ 0.3	$ 0.5