Goodwill (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 585,900,000		$ 585,900,000		$ 586,000,000.0
Accumulated impairment losses	(59,500,000)		(59,500,000)		0
Total	526,400,000		526,400,000		586,000,000.0
Impairment					(59,500,000)
Foreign currency translation					(100,000)
Commercial
Goodwill [Line Items]
Goodwill	376,900,000		376,900,000		377,000,000.0
Accumulated impairment losses	0		0		0
Total	376,900,000		376,900,000		377,000,000.0
Impairment					0
Foreign currency translation					(100,000)
Aviation
Goodwill [Line Items]
Goodwill	209,000,000.0		209,000,000.0		209,000,000.0
Accumulated impairment losses	(59,500,000)		(59,500,000)		0
Total	149,500,000		149,500,000		209,000,000.0
Impairment	$ (59,500,000)	$ 0	$ (59,500,000)	$ 0	(59,500,000)
Foreign currency translation					$ 0