Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Operating results:
Total revenues	$ 83,240	$ 77,909	$ 74,355	$ 66,824	$ 66,965	$ 65,280	$ 63,069	$ 62,340	$ 302,328	$ 257,654	$ 209,625
Gross profit	38,778	34,029	30,530	23,521	24,176	23,601	22,074	21,748
Other expenses	73,589	55,123	59,166	55,267	53,903	50,767	49,292	52,265
Interest expense and other income (expense), net	(386)	(1,999)	(1,885)	(2,271)	(2,128)	(2,332)	(6,493)	(2,252)
Income tax expense	14	(44)	(1,895)	(74)	14	(118)	(113)	(104)	(1,999)	(321)	(454)
Net loss	$ (35,183)	$ (23,137)	$ (32,416)	$ (34,091)	$ (31,841)	$ (29,616)	$ (33,824)	$ (32,873)	$ (124,827)	$ (128,154)	$ (137,628)
Per share data:
Net loss - basic (in dollars per share)	$ (0.46)	$ (0.33)	$ (0.48)	$ (0.54)	$ (0.51)	$ (0.49)	$ (0.62)	$ (0.61)	$ (1.79)	$ (2.22)	$ (2.58)
Net loss - diluted (in dollars per share)	$ (0.46)	$ (0.33)	$ (0.48)	$ (0.54)	$ (0.51)	$ (0.49)	$ (0.62)	$ (0.61)	$ (1.79)	$ (2.22)	$ (2.59)
Product
Operating results:
Total revenues									$ 269,881	$ 240,366	$ 203,777
Cost of revenues	$ 39,479	$ 40,138	$ 41,382	$ 41,605	$ 40,345	$ 39,477	$ 39,204	$ 39,055	162,604	158,081	135,508
Licensing and other
Operating results:
Total revenues									32,447	17,288	5,848
Cost of revenues	$ 4,983	$ 3,742	$ 2,443	$ 1,698	$ 2,444	$ 2,202	$ 1,791	$ 1,537	$ 12,866	$ 7,974	$ 4,088