Consolidated Statements of Operations - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement [Abstract]
Revenue	$ 68,038,000	$ 55,165,000	$ 43,799,000
Cost of revenue	13,625,000	6,844,000	3,448,000
Gross profit	54,413,000	48,321,000	40,351,000
Operating expenses:
Technology and development	11,140,000	9,925,000	8,586,000
Sales and marketing	25,503,000	25,424,000	28,073,000
General and administrative	29,200,000	20,187,000	20,197,000
Restructuring costs	0	149,000	0
Depreciation and amortization	1,486,000	3,705,000	4,586,000
Mark-to-market	0	57,000	148,000
Total operating expenses	67,329,000	59,447,000	61,590,000
Loss from continuing operations	(12,916,000)	(11,126,000)	(21,239,000)
Interest (expense) and other income, net:
Interest expense	0	(89,000)	(78,000)
Other income, net	4,385,000	1,975,000	1,270,000
Total interest (expense) and other income, net	4,385,000	1,886,000	1,192,000
Loss from continuing operations before income taxes	(8,531,000)	(9,240,000)	(20,047,000)
Provision (benefit) from income taxes	476,000	(10,000)	(347,000)
Loss from continuing operations, net of income taxes	(9,007,000)	(9,230,000)	(19,700,000)
Gain (loss) on sale of discontinued operations, net of income taxes	0	(136,000)	14,626,000
Income from discontinued operations, net of income taxes	0	0	7,301,000
Total income (loss) from discontinued operations, net of income taxes	0	(136,000)	21,927,000
Net income (loss)	$ (9,007,000)	$ (9,366,000)	$ 2,227,000
Net income (loss) per share - basic and diluted
Loss from continuing operations, net of income taxes (usd per share)	$ (0.20)	$ (0.18)	$ (0.39)
Income from discontinued operations, net of income taxes (usd per share)	0	0	0.43
Net income (loss) (usd per share)	$ (0.20)	$ (0.18)	$ 0.04
Weighted-average number of shares of common stock outstanding:
Basic and diluted weighted-average number of shares outstanding (shares)	45,864,500	51,764,506	50,511,366