Restructuring and Impairment Charges (Additional Information) (Detail)	3 Months Ended		12 Months Ended
	Dec. 31, 2016 USD ($) employee	Dec. 31, 2014 USD ($)	Dec. 31, 2016 USD ($) employee	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 471,000		$ 700,000
Restructuring and impairment charges			734,000	$ 0	$ 5,390,000
Pension settlement charge		$ 5,200,000
Employee Severance
Restructuring Cost and Reserve [Line Items]
Restructuring charges			600,000
Expected cost	$ 1,200,000		$ 1,200,000
BrightVolt Inc. | Asset Impairments
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment charges		$ 200,000
Arizona
Restructuring Cost and Reserve [Line Items]
Number of employees | employee	70		70