Stock-Based Compensation Expense Recognition (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 11,697,000	$ 12,170,000	$ 9,236,000
Allocation of Recognized Period Costs, Capitalized Amount	0	0	0
Unrecognized Deferred Tax Assets Related to Excess Tax Benefits from Share Based Compensation	0	0	0
Cost of revenue
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	871,000	546,000	258,000
Sales and marketing
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	5,549,000	2,819,000	2,329,000
Research and development
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	2,470,000	3,039,000	2,482,000
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Allocated Share-based Compensation Expense	$ 2,807,000	$ 5,766,000	$ 4,167,000