Consolidated Statements of Changes in Mandatorily Redeemable Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 Series D Preferred Stock [Member]	Dec. 31, 2012 Series E Preferred Stock [Member]	Dec. 31, 2013 Additional Paid-in Capital [Member]
Issuance of preferred stock, issuance costs	$ 559	$ 185
Initial public offering, issuance cost			$ 7,180