Property and Equipment - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended	9 Months Ended
	Jul. 31, 2015	Apr. 30, 2015	Sep. 30, 2015	Sep. 30, 2015	Feb. 28, 2015
Property, Plant and Equipment [Line Items]
Net gain on insurance settlement				$ 919
Perry County Kentucky Buchanan County Virginia And Wise Virginia Facilities [Member]
Property, Plant and Equipment [Line Items]
Estimated amount of losses to be recovered					$ 1,600
Insurance recoveries for clean up and repairs	$ 1,100	$ 500
Perry County Kentucky Buchanan County Virginia And Wise Virginia Facilities [Member] | General and Administrative [Member]
Property, Plant and Equipment [Line Items]
Net gain on insurance settlement			$ 900	$ 900