Restructuring and Impairment Charges, Excluding Goodwill Impairments, and Divestitures - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Restructuring and impairment charges		$ 7,268	$ 875
Impairment assets at Wheeling Plant	$ 900
Cash proceeds from divestiture		2,500
Cash in escrow related to divestiture		$ 500
Gain on sale of business	700
Severance and Other Employee Costs [Member]
Restructuring Cost and Reserve [Line Items]
Accrued restructuring charges	$ 700