Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Operating results:
Total revenues	$ 66,965	$ 65,280	$ 63,069	$ 62,340	$ 52,050	$ 55,910	$ 52,283	$ 49,382	$ 257,654	$ 209,625	$ 212,512
Cost of revenues	40,345	39,477	39,204	39,055	35,153	33,558	33,709	33,088	158,081	135,508	134,494
Cost of licensing and other revenues	2,444	2,202	1,791	1,537	1,572	1,054	850	612	7,974	4,088	1,080
Gross profit	24,176	23,601	22,074	21,748	15,325	21,298	17,724	15,682
Other expenses	53,903	50,767	49,292	52,265	61,956	47,087	46,095	50,232
Interest expense and other income (expense), net	(2,128)	(2,332)	(6,493)	(2,252)	(405)	(1,914)	(631)	1,117
Income tax expense	14	(118)	(113)	(104)	(181)	(162)	(64)	(47)	(321)	(454)	(142)
Net loss	$ (31,841)	$ (29,616)	$ (33,824)	$ (32,873)	$ (47,217)	$ (27,865)	$ (29,066)	$ (33,480)	$ (128,154)	$ (137,628)	$ (100,327)
Per share data:
Net loss - basic (in dollars per share)	$ (0.51)	$ (0.49)	$ (0.62)	$ (0.61)	$ (0.88)	$ (0.52)	$ (0.55)	$ (0.63)	$ (2.22)	$ (2.58)	$ (1.95)
Net loss - diluted (in dollars per share)	$ (0.51)	$ (0.49)	$ (0.62)	$ (0.61)	$ (0.90)	$ (0.52)	$ (0.55)	$ (0.65)	$ (2.22)	$ (2.59)	$ (1.95)