Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	$ 1,091.1	$ 1,104.7
Intangible assets, Accumulated Amortization	(539.1)	(501.0)
Intangible assets, Net Carrying Amount	552.0	603.7
Intangible assets not subject to amortization:
Trade name	124.3	129.0
FAA air agency certificates	8.7	8.7
Indefinite Lived Intangible Assets Net	133.0	137.7
Total intangible assets, Gross Carrying Amount	1,224.1	1,242.4
Total intangible assets, Net Carrying Amount	685.0	741.4
Customer relationships
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	521.2	532.2
Intangible assets, Accumulated Amortization	(183.2)	(161.9)
Intangible assets, Net Carrying Amount	338.0	370.3
Technology and know-how
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	272.3	277.2
Intangible assets, Accumulated Amortization	(83.0)	(72.0)
Intangible assets, Net Carrying Amount	189.3	205.2
Trade names
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	14.3	14.2
Intangible assets, Accumulated Amortization	(9.4)	(8.8)
Intangible assets, Net Carrying Amount	4.9	5.4
Capitalized software
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	278.5	276.4
Intangible assets, Accumulated Amortization	(259.6)	(254.6)
Intangible assets, Net Carrying Amount	18.9	21.8
Other
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	4.8	4.7
Intangible assets, Accumulated Amortization	(3.9)	(3.7)
Intangible assets, Net Carrying Amount	$ 0.9	$ 1.0