Revenue - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Disaggregation of Revenue [Line Items]
Total net revenue	$ 43,057	$ 40,609	$ 124,516	$ 120,351
Local marketplace
Disaggregation of Revenue [Line Items]
Total net revenue	23,383	19,851	67,576	57,408
Transactions
Disaggregation of Revenue [Line Items]
Total net revenue	9,733	7,891	25,050	21,181
National online advertising
Disaggregation of Revenue [Line Items]
Total net revenue	6,794	9,054	20,666	29,035
Publishing and other
Disaggregation of Revenue [Line Items]
Total net revenue	$ 3,147	3,813	$ 11,224	12,727
Accounting Standards Update 2014-09
Disaggregation of Revenue [Line Items]
Total net revenue		40,609		120,351
Accounting Standards Update 2014-09 | Local marketplace
Disaggregation of Revenue [Line Items]
Total net revenue		19,851		57,408
Accounting Standards Update 2014-09 | Transactions
Disaggregation of Revenue [Line Items]
Total net revenue		7,891		21,181
Accounting Standards Update 2014-09 | National online advertising
Disaggregation of Revenue [Line Items]
Total net revenue		9,054		29,035
Accounting Standards Update 2014-09 | Publishing and other
Disaggregation of Revenue [Line Items]
Total net revenue		3,813		12,727
Accounting Standards Update 2014-09 | As Reported
Disaggregation of Revenue [Line Items]
Total net revenue		40,237		118,223
Accounting Standards Update 2014-09 | As Reported | Local marketplace
Disaggregation of Revenue [Line Items]
Total net revenue		20,130		57,555
Accounting Standards Update 2014-09 | As Reported | Transactions
Disaggregation of Revenue [Line Items]
Total net revenue		7,950		21,102
Accounting Standards Update 2014-09 | As Reported | National online advertising
Disaggregation of Revenue [Line Items]
Total net revenue		8,842		27,516
Accounting Standards Update 2014-09 | As Reported | Publishing and other
Disaggregation of Revenue [Line Items]
Total net revenue		3,315		12,050
Accounting Standards Update 2014-09 | Adoption of ASU 2014-09
Disaggregation of Revenue [Line Items]
Total net revenue		372		2,128
Accounting Standards Update 2014-09 | Adoption of ASU 2014-09 | Local marketplace
Disaggregation of Revenue [Line Items]
Total net revenue		(279)		(147)
Accounting Standards Update 2014-09 | Adoption of ASU 2014-09 | Transactions
Disaggregation of Revenue [Line Items]
Total net revenue		(59)		79
Accounting Standards Update 2014-09 | Adoption of ASU 2014-09 | National online advertising
Disaggregation of Revenue [Line Items]
Total net revenue		212		1,519
Accounting Standards Update 2014-09 | Adoption of ASU 2014-09 | Publishing and other
Disaggregation of Revenue [Line Items]
Total net revenue		$ 498		$ 677