Income Taxes - Changes in Valuation Allowance for Deferred Tax Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Deferred Tax Assets Valuation Allowance [Roll Forward]
Balance at beginning of year	$ 211,865	$ 235,730
Net changes to deferred tax assets, subject to a valuation allowance	5,587	(23,865)
Balance at end of year	$ 217,452	$ 211,865