Restructuring and Impairment Charges - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		6 Months Ended		12 Months Ended
	Apr. 24, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2018	Dec. 31, 2019
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 2.0
Restructuring costs	1.2
Severance and retention expenses	$ 0.8
Arizona
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 0.1	$ 1.1	$ 0.5	$ 1.8
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges		0.3		0.3
Restructuring charges, fair value		1.1
Restructuring costs		0.0	$ 0.1	$ 0.1	$ 0.3
Facility Consolidation
Restructuring Cost and Reserve [Line Items]
Restructuring charges		$ 0.5
Forecast
Restructuring Cost and Reserve [Line Items]
Expected cost to be paid						$ 1.5	$ 0.5
Minimum | Forecast
Restructuring Cost and Reserve [Line Items]
Estimated capital expenditures						1.2
Maximum | Forecast
Restructuring Cost and Reserve [Line Items]
Estimated capital expenditures						$ 1.4