Subsequent Events (Details) (USD $)	0 Months Ended			0 Months Ended
	Jul. 02, 2013	Jun. 30, 2013	Dec. 31, 2012	Jul. 02, 2013 Common Stock IPO - conversion of mandatorily redeemable convertible preferred stock	Jul. 02, 2013 Common Stock IPO - conversion of mandatorily redeemable convertible preferred stock, Series F	Jul. 02, 2013 Common Stock IPO - conversion of Series II common stock	Jul. 02, 2013 Subsequent event	Jul. 30, 2013 Subsequent event Revolving working capital credit facility	Jul. 02, 2013 Subsequent event Common Stock IPO - conversion of mandatorily redeemable convertible preferred stock	Jul. 02, 2013 Subsequent event Common Stock IPO - conversion of mandatorily redeemable convertible preferred stock, Series F	Jul. 02, 2013 Subsequent event Common Stock IPO - conversion of Series II common stock
Subsequent events
Common stock sold and issued in IPO (in shares)	7,500,000						7,500,000
Issuance price (in dollars per share)					$ 10.00		$ 10.00
Net proceeds from qualified initial public offering							$ 66,800,000
Underwriting discount, commissions and offering costs							8,200,000
Common stock issued on automatic conversion of preferred stock (in shares)				34,172,316	5,549,989	1,052,464			34,172,316		1,052,464
Shares of common stock issued on conversion related to the ratchet provision					1,584,863					1,584,863
Common stock, shares authorized		102,333,333	52,333,333				250,000,000
Shares of preferred stock that may be issued		32,742,929	32,742,929				10,000,000
Repayments of principal borrowings and accrued, but unpaid interest expenses								$ 6,033,000