Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Preferred stock, shares authorized	136,074,466	135,913,741
Preferred stock, shares issued	17,357,903	17,266,628
Preferred stock, shares outstanding	17,357,903	17,266,628
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	180,000,000	180,000,000
Common stock, shares issued	1,616,514	1,588,701
Common stock, shares outstanding	1,616,514	1,588,701
Convertible Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	1,843,894	1,843,894
Preferred stock, shares issued	224,564	224,564
Preferred stock, shares outstanding	224,564	224,564
Preferred stock, aggregate liquidation preference	$ 2.5	$ 2.5
Redeemable Convertible Preferred Stock [Member]
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	134,230,572	134,069,847
Preferred stock, shares issued	17,133,339	17,042,064
Preferred stock, shares outstanding	17,133,339	17,042,064
Preferred stock, aggregate liquidation preference	$ 107.9	$ 103.5