Goodwill and Other Intangible Assets - Intangible Assets (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	$ 1,096.8	$ 1,104.7
Intangible assets, Accumulated Amortization	(527.7)	(501.0)
Intangible assets, Net Carrying Amount	569.1	603.7
Intangible assets not subject to amortization:
Trade name	126.4	129.0
FAA air agency certificates	8.7	8.7
Indefinite Lived Intangible Assets Net	135.1	137.7
Total intangible assets, Gross Carrying Amount	1,231.9	1,242.4
Total intangible assets, Net Carrying Amount	704.2	741.4
Customer relationships
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	526.4	532.2
Intangible assets, Accumulated Amortization	(176.7)	(161.9)
Intangible assets, Net Carrying Amount	349.7	370.3
Technology and know-how
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	273.9	277.2
Intangible assets, Accumulated Amortization	(79.7)	(72.0)
Intangible assets, Net Carrying Amount	194.2	205.2
Trade names
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	14.3	14.2
Intangible assets, Accumulated Amortization	(9.2)	(8.8)
Intangible assets, Net Carrying Amount	5.1	5.4
Capitalized software
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	277.5	276.4
Intangible assets, Accumulated Amortization	(258.2)	(254.6)
Intangible assets, Net Carrying Amount	19.3	21.8
Other
Intangible assets subject to amortization:
Intangible assets, Gross Carrying Amount	4.7	4.7
Intangible assets, Accumulated Amortization	(3.9)	(3.7)
Intangible assets, Net Carrying Amount	$ 0.8	$ 1.0