Redeemable Convertible Preferred Stock - Series B Preferred Stock - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Temporary Equity [Line Items]
Redeemable convertible preferred stock, outstanding shares		25,000,000
Exchange of outstanding convertible notes and accrued interest into Series A redeemable convertible preferred stock and tranche rights	$ 150,187,000	$ 2,929,000
Redeemable Convertible Preferred Stock
Temporary Equity [Line Items]
Redeemable convertible referred stock, authorized shares	0	45,000,000
Redeemable convertible preferred stock, issued (in shares)	0	25,000,000
Redeemable convertible preferred stock, outstanding shares	0
Redeemable convertible preferred stock, aggregate liquidation preference (in dollars)		$ 26,086
Redeemable Convertible Preferred Stock Series B
Temporary Equity [Line Items]
Redeemable convertible referred stock, authorized shares	30,000,001
Redeemable convertible preferred stock, issued (in shares)	30,000,001
Price per share	$ 3.00
Proceeds from issuance of stock, net of issuance costs	$ 89,780,000
Issuance costs	220,000
Discount recorded against proceeds received for temporary equity related to payment in excess over fair value	$ 5,000,000