Cash, Cash Equivalents and Short-Term Investments - Additional Information (Detail) - USD ($)	12 Months Ended
	Dec. 31, 2015	Sep. 30, 2016
Cash And Cash Equivalents [Abstract]
Available-for-sale securities	$ 192,491,000	$ 0
Weighted average maturity period of available-for-sale securities	4 months
Short-term investments	$ 112,187,000