Segment and Geographic Information - Product Sales Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information
Sales	$ 290.1	$ 272.2	$ 277.9	$ 244.1	$ 269.4	$ 202.7	$ 199.8	$ 171.0	$ 1,084.3	$ 842.9	$ 722.0
Natural gas processing (including petrochemical) applications
Segment Reporting Information
Sales									262.1	152.9	105.4
Liquefied natural gas (LNG) applications
Segment Reporting Information
Sales									175.6	167.5	146.9
Industrial gas production applications
Segment Reporting Information
Sales									13.6	22.4	10.7
HVAC, power and refining applications
Segment Reporting Information
Sales									74.2	20.8	0.0
Bulk industrial gas applications
Segment Reporting Information
Sales									273.6	222.5	230.7
Packaged gas industrial applications
Segment Reporting Information
Sales									204.8	179.8	157.7
Cryobiological storage
Segment Reporting Information
Sales									80.4	77.0	70.6
Operating Segments | Energy & Chemicals
Segment Reporting Information
Sales									390.5	225.6	154.3
Operating Segments | Energy & Chemicals | Natural gas processing (including petrochemical) applications
Segment Reporting Information
Sales									262.1	152.9	105.4
Operating Segments | Energy & Chemicals | Liquefied natural gas (LNG) applications
Segment Reporting Information
Sales									40.6	29.5	38.2
Operating Segments | Energy & Chemicals | Industrial gas production applications
Segment Reporting Information
Sales									13.6	22.4	10.7
Operating Segments | Energy & Chemicals | HVAC, power and refining applications
Segment Reporting Information
Sales									74.2	20.8	0.0
Operating Segments | Energy & Chemicals | Bulk industrial gas applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | Energy & Chemicals | Packaged gas industrial applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | Energy & Chemicals | Cryobiological storage
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S West
Segment Reporting Information
Sales									455.5	400.6	378.1
Operating Segments | D&S West | Natural gas processing (including petrochemical) applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S West | Liquefied natural gas (LNG) applications
Segment Reporting Information
Sales									71.7	58.0	45.9
Operating Segments | D&S West | Industrial gas production applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S West | HVAC, power and refining applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S West | Bulk industrial gas applications
Segment Reporting Information
Sales									148.5	129.6	141.4
Operating Segments | D&S West | Packaged gas industrial applications
Segment Reporting Information
Sales									153.4	136.0	120.2
Operating Segments | D&S West | Cryobiological storage
Segment Reporting Information
Sales									81.9	77.0	70.6
Operating Segments | D&S East
Segment Reporting Information
Sales									246.3	232.3	197.6
Operating Segments | D&S East | Natural gas processing (including petrochemical) applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S East | Liquefied natural gas (LNG) applications
Segment Reporting Information
Sales									65.3	80.2	67.0
Operating Segments | D&S East | Industrial gas production applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S East | HVAC, power and refining applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Operating Segments | D&S East | Bulk industrial gas applications
Segment Reporting Information
Sales									126.1	93.4	90.1
Operating Segments | D&S East | Packaged gas industrial applications
Segment Reporting Information
Sales									54.9	58.7	40.5
Operating Segments | D&S East | Cryobiological storage
Segment Reporting Information
Sales									0.0	0.0	0.0
Intersegment Eliminations
Segment Reporting Information
Sales									(8.0)	(15.6)	(8.0)
Intersegment Eliminations | Natural gas processing (including petrochemical) applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Intersegment Eliminations | Liquefied natural gas (LNG) applications
Segment Reporting Information
Sales									(2.0)	(0.2)	(4.2)
Intersegment Eliminations | Industrial gas production applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Intersegment Eliminations | HVAC, power and refining applications
Segment Reporting Information
Sales									0.0	0.0	0.0
Intersegment Eliminations | Bulk industrial gas applications
Segment Reporting Information
Sales									(1.0)	(0.5)	(0.8)
Intersegment Eliminations | Packaged gas industrial applications
Segment Reporting Information
Sales									(3.5)	(14.9)	(3.0)
Intersegment Eliminations | Cryobiological storage
Segment Reporting Information
Sales									$ (1.5)	$ 0.0	$ 0.0