Income Taxes Components of income tax expense/ (benefit) (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Federal:
Current									$ 0	$ 0	$ 0
Deferred									0	0	0
Total federal provision									0	0	0
State:
Current									20	16	17
Deferred									0	0	0
Total state provision									20	16	17
Foreign:
Current									30	195	294
Deferred									0	0	0
Total foreign provision									30	195	294
Total income tax expense	$ (14)	$ (10)	$ 61	$ 13	$ 97	$ 33	$ 106	$ (25)	$ 50	$ 211	$ 311