Domestic and Foreign Operations - Schedule of Revenues and Gross Profit by Regions (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Services revenue
Services revenue	$ 1,086.9	$ 1,663.7	$ 1,468.4
Gross profit
Gross profit	30.4	228.1	184.0
Lease Type Contracts
Services revenue
Services revenue	189.4	408.9	413.9
Gross profit
Gross profit	(5.6)	42.0	36.3
Management Type Contracts
Services revenue
Services revenue	359.6	526.0	361.5
Gross profit
Gross profit	133.1	186.1	147.7
Reimbursed Management Type Contract Revenue
Services revenue
Services revenue	537.9	728.8	693.0
Lease Impairment
Gross profit
Gross profit	97.1	0.0	0.0
Operating Segments | Lease Impairment
Gross profit
Gross profit	(97.1)
Operating Segments | Commercial
Services revenue
Services revenue	392.3	641.9	635.6
Gross profit
Gross profit	(27.4)	133.6	124.1
Operating Segments | Commercial | Lease Type Contracts
Services revenue
Services revenue	180.2	377.3	386.2
Gross profit
Gross profit	$ (10.4)	$ 29.5	$ 25.8
Gross margin percentage	(5.80%)	7.80%	6.70%
Operating Segments | Commercial | Management Type Contracts
Services revenue
Services revenue	$ 212.1	$ 264.6	$ 249.4
Gross profit
Gross profit	$ 80.1	$ 104.1	$ 98.3
Gross margin percentage	37.80%	39.30%	39.40%
Operating Segments | Aviation
Services revenue
Services revenue	$ 149.1	$ 282.5	$ 128.2
Gross profit
Gross profit	40.6	74.4	39.2
Operating Segments | Aviation | Lease Type Contracts
Services revenue
Services revenue	8.6	30.7	27.0
Gross profit
Gross profit	$ 0.7	$ 8.2	$ 7.3
Gross margin percentage	8.10%	26.70%	27.00%
Operating Segments | Aviation | Management Type Contracts
Services revenue
Services revenue	$ 140.5	$ 251.8	$ 101.2
Gross profit
Gross profit	$ 39.9	$ 66.2	$ 31.9
Gross margin percentage	28.40%	26.30%	31.50%
Segment Reconciling Items
Services revenue
Services revenue	$ 7.6	$ 10.5	$ 11.6
Gross profit
Gross profit	17.2	20.1	20.7
Segment Reconciling Items | Lease Type Contracts
Services revenue
Services revenue	0.6	0.9	0.7
Gross profit
Gross profit	4.1	4.3	3.2
Segment Reconciling Items | Management Type Contracts
Services revenue
Services revenue	7.0	9.6	10.9
Gross profit
Gross profit	$ 13.1	$ 15.8	$ 17.5