Debt Obligations - Additional Information (Details) (USD $)	0 Months Ended	9 Months Ended							9 Months Ended		0 Months Ended		0 Months Ended
	Jun. 06, 2014	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Convertible notes	Jan. 31, 2011 Convertible notes Convertible notes issued January 2011	Jun. 30, 2011 Convertible notes Convertible debt issued June 2011	Jan. 31, 2011 Trusts related to two co-founders Convertible notes Related party convertible notes issued January 2011	Sep. 30, 2014 Common Stock	Sep. 30, 2014 Common Stock Convertible notes payable	Jun. 06, 2014 Common Stock	Jun. 06, 2014 Common Stock	Jun. 06, 2014 Common Stock Convertible notes payable
Debt Instrument [Line Items]
Aggregate principal amount						$ 55,000,000	$ 20,000,000	$ 25,000,000
Issuance of common stock during IPO (in shares)									6,038,000		6,037,500
Issuance of common stock from initial public offering, net of offering costs	238,900,000	238,904,000							1,000
Unamortized debt discount				1,207,000
Interest rate					6.00%
Minimum amount of indebtedness not subject to acceleration of maturity after failure to make other payment obligations					10,000,000
Prepay notice period		10 days
Issue price (usd per share)												$ 43
Repayment of Notes Payable and Accrued Interest	23,600,000
Repayment on notes payable		20,000,000	0
Withholding taxes	1,100,000
Converted debt amount	$ 96,500,000
Shares issued upon conversion										1,543,000	24,000,000		2,200,000