Goodwill and Intangible Assets - Narrative (Details)	3 Months Ended
	Mar. 31, 2018 USD ($) operating_segment reporting_unit	Dec. 31, 2017 USD ($)	Mar. 31, 2017 USD ($)
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 12,876,000	$ 12,876,000
Number of operating segments | operating_segment	1
Number of reporting units | reporting_unit	1
Impairment of goodwill	$ 0
Amortization of acquired intangibles	368,000		$ 371,000
Capitalized software development costs	4,000,000	4,000,000
Amortization of capitalized software development costs	$ 200,000		100,000
Minimum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	2 years
Maximum
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	6 years
Maximum | Capitalized software development costs
Finite-Lived Intangible Assets [Line Items]
Estimated useful life	5 years
Cost of revenues
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangibles	$ 900,000	$ 900,000
Operating expenses
Finite-Lived Intangible Assets [Line Items]
Amortization of acquired intangibles	$ 400,000		$ 400,000