Revenue - Disaggregation of Revenue (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
Disaggregation of Revenue [Line Items]
Net sales	$ 110.9	$ 129.1	$ 128.2	$ 119.7	$ 116.1	$ 115.2	$ 106.6	$ 103.4	$ 487.9	$ 441.3	$ 414.8
General industrial
Disaggregation of Revenue [Line Items]
Net sales									174.6	145.2	131.4
Transportation
Disaggregation of Revenue [Line Items]
Net sales									151.8	130.3	135.8
Defense and emergency
Disaggregation of Revenue [Line Items]
Net sales									128.7	130.6	119.3
Healthcare
Disaggregation of Revenue [Line Items]
Net sales									32.8	35.2	28.3
Gas Cylinders segment
Disaggregation of Revenue [Line Items]
Net sales									238.1	220.2	225.8
Gas Cylinders segment | General industrial
Disaggregation of Revenue [Line Items]
Net sales									50.7	49.6	45.7
Gas Cylinders segment | Transportation
Disaggregation of Revenue [Line Items]
Net sales									79.0	63.8	72.9
Gas Cylinders segment | Defense and emergency
Disaggregation of Revenue [Line Items]
Net sales									79.3	76.5	83.1
Gas Cylinders segment | Healthcare
Disaggregation of Revenue [Line Items]
Net sales									29.1	30.3	24.1
Elektron segment
Disaggregation of Revenue [Line Items]
Net sales									249.8	221.1	189.0
Elektron segment | General industrial
Disaggregation of Revenue [Line Items]
Net sales									123.9	95.6	85.7
Elektron segment | Transportation
Disaggregation of Revenue [Line Items]
Net sales									72.8	66.5	62.9
Elektron segment | Defense and emergency
Disaggregation of Revenue [Line Items]
Net sales									49.4	54.1	36.2
Elektron segment | Healthcare
Disaggregation of Revenue [Line Items]
Net sales									$ 3.7	$ 4.9	$ 4.2