Quarterly Financial Information (Unaudited) - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Line Items]
Gain (loss) on change in the fair value of the derivative liability		$ (20,200)
Impairment charge	$ 16,300			$ 19,200
Other gains and (losses), net			$ 4,161	$ (10,889)	$ 23,400
Aurora [Member]
Selected Quarterly Financial Information [Line Items]
Other gains and (losses), net	$ 6,900