Segment Information - By Reportable Segment (Details) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018 USD ($)	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) segment	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Segment Reporting [Abstract]
Number of reportable segments | segment			2
Segment Reporting Information [Line Items]
Net sales	$ 363.1	$ 313.0	$ 718.3	$ 615.5	$ 1,265.4
Operating income from continuing operations	25.3	21.7	45.4	34.1	$ 71.3
Reportable Segments | IPG
Segment Reporting Information [Line Items]
Net sales	231.2	202.7	443.4	392.9
Operating income from continuing operations	23.0	22.9	39.3	35.4
Reportable Segments | ETG
Segment Reporting Information [Line Items]
Net sales	131.9	110.3	274.9	222.6
Operating income from continuing operations	7.2	5.7	16.5	11.5
Reportable Segments | NATG
Segment Reporting Information [Line Items]
Operating income from continuing operations	0.0	(0.4)	0.0	(0.4)
Corporate and Other
Segment Reporting Information [Line Items]
Operating income from continuing operations	$ (4.9)	$ (6.5)	$ (10.4)	$ (12.4)