Capitalization (Details) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2014	Feb. 18, 2014	Sep. 30, 2013
Capital structure
Net proceeds, after deducting underwriters' discounts and commissions and other offering expense	$ 55,409,000
Common stock.
Capital structure
Issuance of common stock from offering, net (in shares)		1,900,000	8,740,000
Price of common stock issued in initial public offering (in dollars per share)			$ 22.00
Net proceeds from issuance of shares of common stock after deducting underwriters' discount and commissions and other offering expenses (in dollars)			175,600,000
Shares issued on automatic conversion of redeemable convertible preferred stock			21,038,477
Shares of common stock offered in follow on offering		2,628,571
Offering price (in dollars per share)		$ 31.50
Shares sold by selling stockholders in follow on offering		728,571
Shares sold by selling stockholders upon full exercise by underwriters of their option to purchase additional shares		342,857
Net proceeds, after deducting underwriters' discounts and commissions and other offering expense		$ 55,400,000