Significant Accounting Policies (Tables)

3 Months Ended

Mar. 31, 2017

Accounting Policies [Abstract]

Schedule of common stock equivalents excluded due to anti-dilutive effect

	As of March 31,
	2016	2017
Outstanding common stock options	6,479,347	6,860,968
Outstanding warrants	34,647	34,647
Outstanding PRSUs	213,758	—
Outstanding RSUs	469,705	616,912
Shares to be purchased under the ESPP	29,651	30,121
Total	7,227,108	7,542,648