Income Tax - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Percentage of annual effective income tax rate	0.27%
Valuation allowance	$ 362,558,000	$ 292,271,000
U.S. federal tax loss carryforwards ("NOL")	$ 426,000,000
Tax loss carryforwards expiration year	2034
Reserve for uncertain tax positions	$ 0	$ 0	$ 0