Fair Value Measurements - Additional Information (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Other than Temporary Impairment Losses, Investments	$ 500	$ 1,900
Short-term investments	$ 2,181	$ 4,600	$ 0