Income Taxes - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Line Items]
Deferred income tax provision (benefit)	$ (4,600,000)	$ 0	$ 0
Amount of prepaid tax amortized to income tax expense	200,000	200,000	200,000
Deferred tax assets valuation allowance increase	74,400,000	61,200,000	80,800,000
Interest expense	110,000	$ 84,000	$ 65,000
Increase in liability for uncertain tax positions	25,500,000
Tax benefit that would be recognized if unrecognized tax benefits were realized and not subject to valuation allowances	21,900,000
Federal
Income Taxes [Line Items]
Net operating loss carryforwards related to stock-based compensation tax deductions	$ 35,000,000