Selected Quarterly Financial Data (Unaudited) - Unaudited Quarterly Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended									12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement of Operations Data:
Revenue	$ 5,854	$ 5,011	$ 3,971	$ 3,440	$ 2,901		$ 2,905	$ 2,182	$ 1,588	$ 18,276	$ 9,576	$ 1,278
Cost of revenue	1,863	2,143	1,411	1,304	2,726		918	772	653	6,722	5,069	936
Gross profit	3,991	2,868	2,560	2,136	175		1,987	1,410	935	11,554	4,507	342
Operating expenses:
Research and development	818	1,523	656	561	3,650		312	252	217	3,558	4,431	521
Selling and marketing	798	893	477	301	1,913		280	243	234	2,469	2,670	581
General and administrative	1,116	1,147	457	1,889	1,956		215	168	79	4,609	2,418	230
Total operating expenses	2,732	3,563	1,590	2,751	7,519		807	663	530	10,636	9,519	1,332
Operating income (loss)	1,259	(695)	970	(615)	(7,344)		1,180	747	405	918	(5,012)	(990)
Interest and other income (expense)	57	5	(5,462)	13	7				20	(5,386)	27	0
Income (loss) before income taxes	1,316	(690)	(4,492)	(602)	(7,337)		1,180	747	425	(4,468)	(4,985)	(990)
Provision for income taxes	503	417								920	0	0
Net income (loss)	$ 813	$ (1,107)	$ (4,492)	$ (602)	$ (7,337)	$ (8,135)	$ 1,180	$ 747	$ 425	$ (5,347)	$ (8,314)	$ (4,283)
Basic and diluted income (loss) per common share:
Basic	$ 0.05	$ (0.44)	$ (5.49)	$ (0.02)	$ (0.61)
Diluted	$ 0.05	$ (0.44)	$ (5.49)	$ (0.02)	$ (0.61)