Selected Quarterly Financial Data (unaudited) - Quarterly Financial Data (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended											12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue from Contract with Customer, Including Assessed Tax	$ 132,588	$ 117,399	$ 103,155	$ 169,143	$ 114,890	$ 50,894	$ 38,267	$ 73,692				$ 522,285	$ 277,743	$ 191,603
Cost of Goods and Services Sold												206,572	121,601	79,872
Gross profit	82,132	69,642	57,668	106,271	59,127				$ 29,690	$ 18,826	$ 48,499	315,713	156,142	111,731
Operating income (loss)	27,538	16,894	404	51,093	3,887				(2,537)	(11,027)	19,229	95,929	9,552	(4,439)
Net income (loss)	$ 32,479	$ 10,822	$ (3,076)	$ 33,958	$ (5,088)				$ (5,525)	$ (11,842)	$ 14,290	$ 74,183	$ (8,165)	$ (13,808)
Basic and diluted loss per share	$ 0.82	$ 0.28	$ (0.08)	$ 0.96	$ (0.15)				$ (0.16)	$ (0.35)	$ 0.43
Diluted net earnings (loss) per share	$ 0.78	$ 0.27	$ (0.08)	$ 0.86	$ (0.15)				$ (0.16)	$ (0.35)	$ 0.42	$ 1.86	$ (0.24)	$ (0.42)