Income Taxes - Summary of Changes in Deferred Tax Asset Valuation Allowance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 70,629	$ 53,923	$ 36,012
Balance at End of Year	88,453	70,629	53,923
Valuation Allowance of Deferred Tax Assets
Movement in Valuation Allowances and Reserves [Roll Forward]
Charged to Costs and Expenses	17,824	16,706	17,911
Write-offs	$ 0	$ 0	$ 0