Restructuring Activities - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 1,381,000	$ 2,206,000
2015 California manufacturing operations restructuring plan
Restructuring Cost and Reserve [Line Items]
Restructuring expenses	$ 0	$ 2,200,000