Business Segments - Financial Performance by Segment and Reconciliation (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Segment Revenue:
Total revenue	$ 40,030	$ 41,456	$ 109,857	$ 109,523
Segment Operating Expenses:
Consolidated operating expenses	39,730	41,345	117,122	111,497
Segment operating contribution and Reconciliation to consolidated pre-tax income (loss):
Adjusted EBITDA	300	128	(7,265)	(1,733)
Add (deduct)
Interest income (expense), net	39	114	217	160
Other income (expense), net	(6)	(59)	6	(92)
Depreciation and amortization	(2,362)	(2,687)	(7,740)	(7,588)
Stock-based compensation	(2,460)	(2,502)	(6,590)	(7,386)
Acquisition, disposition, realignment and contingent payment costs		(1,016)	(90)	(1,555)
Loss before income taxes	(4,489)	(6,022)	(21,462)	(18,194)
Corporate
Segment Operating Expenses:
Consolidated operating expenses	7,179	6,774	22,343	20,363
Segment operating contribution and Reconciliation to consolidated pre-tax income (loss):
Adjusted EBITDA	(7,179)	(6,774)	(22,343)	(20,363)
Acquisition, disposition and realignment costs
Segment operating contribution and Reconciliation to consolidated pre-tax income (loss):
Adjusted EBITDA		17		241
Marketplaces
Segment Revenue:
Total revenue	23,327	24,712	63,354	65,334
Marketplaces | Operating Segments
Segment Operating Expenses:
Consolidated operating expenses	22,512	24,386	65,194	65,498
Segment operating contribution and Reconciliation to consolidated pre-tax income (loss):
Adjusted EBITDA	815	326	(1,840)	(164)
Media
Segment Revenue:
Total revenue	16,703	16,744	46,503	44,189
Media | Operating Segments
Segment Operating Expenses:
Consolidated operating expenses	10,039	10,185	29,585	25,636
Segment operating contribution and Reconciliation to consolidated pre-tax income (loss):
Adjusted EBITDA	$ 6,664	$ 6,559	$ 16,918	$ 18,553