Goodwill - Schedule of Changes in Carrying Amounts of Goodwill (Details) - USD ($)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Goodwill [Line Items]
Goodwill	$ 586,100,000	$ 586,000,000.0	$ 585,500,000
Accumulated impairment losses	(59,500,000)
Total	526,600,000	586,000,000.0	585,500,000
Purchase price adjustments		300,000
Impairment	(59,500,000)	0	0
Foreign currency translation	100,000	200,000
Commercial
Goodwill [Line Items]
Goodwill	377,100,000	377,000,000.0	376,800,000
Total	377,100,000	377,000,000.0	376,800,000
Purchase price adjustments		0
Foreign currency translation	100,000	200,000
Aviation
Goodwill [Line Items]
Goodwill	209,000,000.0	209,000,000.0	208,700,000
Accumulated impairment losses	(59,500,000)
Total	149,500,000	209,000,000.0	$ 208,700,000
Purchase price adjustments		300,000
Impairment	(59,500,000)
Foreign currency translation	$ 0	$ 0