Stockholders' Equity and Employee Stock Option Plans (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Stock-based Compensation Expense
Stock-based Compensation Expense, Total	$ 509	$ 442	$ 953	$ 909
Cost of Revenues [Member]
Stock-based Compensation Expense
Stock-based Compensation Expense, Total	60	45	118	74
Product development [Member]
Stock-based Compensation Expense
Stock-based Compensation Expense, Total	105	119	199	243
Sales and marketing [Member]
Stock-based Compensation Expense
Stock-based Compensation Expense, Total	91	27	179	129
General and administrative [Member]
Stock-based Compensation Expense
Stock-based Compensation Expense, Total	$ 253	$ 251	$ 457	$ 463