Revenues - Revenues, Disaggregation of Revenues (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Disaggregation Of Revenue [Line Items]
Revenues		$ 11,728	$ 13,153	$ 37,652	$ 42,806
Subscriptions [Member]
Disaggregation Of Revenue [Line Items]
Revenues		8,696	12,884	28,548	41,795
Strategic Agreements [Member]
Disaggregation Of Revenue [Line Items]
Revenues		3,032	269	9,104	1,011
United States of America [Member]
Disaggregation Of Revenue [Line Items]
Revenues		8,802	9,192	28,135	28,987
United Kingdom [Member]
Disaggregation Of Revenue [Line Items]
Revenues		1,312	1,755	4,340	5,877
Other [Member]
Disaggregation Of Revenue [Line Items]
Revenues	[1]	$ 1,614	$ 2,206	$ 5,177	$ 7,942

[1] No individual country within the “Other” category accounted for 10% or more of revenues, net for any period presented.