Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	$ 1,091.3	$ 1,104.7
Intangible assets, Accumulated Amortization	(512.8)	(501.0)
Intangible assets, Net Carrying Amount	578.5	603.7
Intangible assets not subject to amortization:
Trade name	125.4	129.0
FAA air agency certificates	8.7	8.7
Indefinite Lived Intangible Assets Net	134.1	137.7
Total intangible assets, Gross Carrying Amount	1,225.4	1,242.4
Total intangible assets, Net Carrying Amount	712.6	741.4
Customer relationships
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	523.6	532.2
Intangible assets, Accumulated Amortization	(168.6)	(161.9)
Intangible assets, Net Carrying Amount	355.0	370.3
Technology and know-how
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	272.4	277.2
Intangible assets, Accumulated Amortization	(75.3)	(72.0)
Intangible assets, Net Carrying Amount	197.1	205.2
Trade names
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	14.2	14.2
Intangible assets, Accumulated Amortization	(9.0)	(8.8)
Intangible assets, Net Carrying Amount	5.2	5.4
Capitalized software
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	276.5	276.4
Intangible assets, Accumulated Amortization	(256.1)	(254.6)
Intangible assets, Net Carrying Amount	20.4	21.8
Other
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	4.6	4.7
Intangible assets, Accumulated Amortization	(3.8)	(3.7)
Intangible assets, Net Carrying Amount	$ 0.8	$ 1.0