Revenue Contract Acquisition Costs (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Capitalized Contract Cost [Line Items]
Capitalized contract cost, amortization	$ 207,000	$ 382,000
Deferred Commissions [Member]
Capitalized Contract Cost [Line Items]
Capitalized contract costs, current	268,000		$ 308,000
Capitalized contract costs, noncurrent	$ 59,000		$ 47,000