Property, Plant and Equipment - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation and amortization expenses		$ 8.8	$ 12.6	$ 13.2
Costs related to terminated manufacturing obligations	$ 0.9
Manufacturing Equipment [Member]
Property, Plant and Equipment [Line Items]
Original cost of impaired equipment	23.4		23.4
Net book value of impaired equipment	$ 15.1		$ 15.1