Stockholders' Equity and Redeemable Convertible Preferred Stock (Details 5) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Total compensation expense	$ 47	$ 6,992	$ 134	$ 10,388
Employee restricted stock awards [Member]
Total compensation expense		12	11	14
Employee stock option awards [Member]
Total compensation expense	$ 14	6,757	90	10,150
Non-employee restricted stock awards [Member]
Total compensation expense	$ 33	175	$ 33	176
Non-employee stock option awards [Member]
Total compensation expense		$ 48		$ 48