Intangible Assets - Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Impairment of intangible assets	$ 0
Accumulated amortization	5,251,000	$ 4,568,000
Amortization expense	$ 683,000	$ 869,000
Minimum
Business Acquisition [Line Items]
Intangible assets, estimated useful life	5 years
Maximum
Business Acquisition [Line Items]
Intangible assets, estimated useful life	12 years
Customer relationships
Business Acquisition [Line Items]
Intangible assets, estimated useful life	5 years
Accumulated amortization	$ 4,335,000
Affiliate network
Business Acquisition [Line Items]
Intangible assets, estimated useful life	12 years
Accumulated amortization	$ 528,000
Trademarks
Business Acquisition [Line Items]
Intangible assets, estimated useful life	8 years
Accumulated amortization	$ 388,000