Redeemable Convertible Preferred Stock - Tranche Rights Issued with Series A Preferred Stock - (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair value of Tranche Rights
Fair value of Tranche Right Liability	$ (6,305,000)
Total Fair value of Tranche Right Asset (Liability)		$ (6,305,000)
Change in fair value of preferred stock tranche liability	9,750,000	1,949,000
Accrued dividends on temporary equity	1,245,000
Tranche Right I
Fair value of Tranche Rights
Proceeds from issuance of stock, net of issuance costs		18,491,000
Other financing expense | Tranche Right I
Fair value of Tranche Rights
Change in fair value of preferred stock tranche liability		261,000
Other financing expense | Tranche Right II
Fair value of Tranche Rights
Change in fair value of preferred stock tranche liability	$ 9,750,000	$ 2,210,000
Redeemable Convertible Preferred Stock Series A
Temporary Equity [Line Items]
Price per share	$ 1.00	$ 1.00
Fair value of Tranche Rights
Total Fair value of Tranche Right Asset (Liability)	$ (2,600,000)
Proceeds from issuance of stock, net of issuance costs	$ 32,000
Redeemable convertible preferred stock, initial carrying amount		$ 21,979,000
Redeemable Convertible Preferred Stock Series A | Tranche Right I
Temporary Equity [Line Items]
Number of additional shares of temporary equity contingently obligated to be purchased by temporary equity holders	18,500,000
Price per share	$ 1.00
Fair value of Tranche Rights
Fair value of Tranche Right Asset	$ 1,495,000
Issuance of stock (in shares)		18,500,000
Redeemable Convertible Preferred Stock Series A | Tranche Right II
Temporary Equity [Line Items]
Number of additional shares of temporary equity contingently obligated to be purchased by temporary equity holders	20,000,000
Fair value of Tranche Rights
Fair value of Tranche Right Liability	$ (4,095,000)
Redeemable convertible preferred stock, initial carrying amount	36,054,000
Accrued dividends on temporary equity	$ 1,245,000
Redeemable Convertible Preferred Stock Series B
Temporary Equity [Line Items]
Price per share	$ 3.00
Fair value of Tranche Rights
Proceeds from issuance of stock, net of issuance costs	$ 89,780,000