Consolidated Statements of Convertible and Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Common Stock [Member]
Issuance of common stock in connection with initial public offering, issuance costs	$ 14.8
Series D Redeemable Convertible Preferred Stock [Member]
Issuance of Series D redeemable convertible preferred stock, issuance costs		$ 3.3