Restructuring - Additional Information (Details) - USD ($)	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred	$ 0
Remaining provision		$ 800,000
Employee Separation, Facility and Other Costs
Restructuring Cost and Reserve [Line Items]
Utilized funds		(900,000)
Employee Separation, Facility and Other Costs | Monona Facility
Restructuring Cost and Reserve [Line Items]
Restructuring costs incurred		$ 2,000,000