Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Revenue	$ 71,315	$ 53,013	$ 139,347	$ 101,506
Subscription and support
Disaggregation of Revenue [Line Items]
Revenue	67,699	48,715	131,590	93,698
Subscription and support | United States
Disaggregation of Revenue [Line Items]
Revenue	50,619	34,436	96,590	64,275
Subscription and support | United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	9,350	9,432	19,346	18,748
Subscription and support | Canada
Disaggregation of Revenue [Line Items]
Revenue	3,360	1,348	7,942	3,732
Subscription and support | Other International
Disaggregation of Revenue [Line Items]
Revenue	4,370	3,499	7,712	6,943
Perpetual license
Disaggregation of Revenue [Line Items]
Revenue	491	575	852	1,232
Perpetual license | United States
Disaggregation of Revenue [Line Items]
Revenue	222	484	504	1,052
Perpetual license | United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	0	8	16	17
Perpetual license | Canada
Disaggregation of Revenue [Line Items]
Revenue	36	15	57	57
Perpetual license | Other International
Disaggregation of Revenue [Line Items]
Revenue	233	68	275	106
Professional services
Disaggregation of Revenue [Line Items]
Revenue	3,125	3,723	6,905	6,576
Professional services | United States
Disaggregation of Revenue [Line Items]
Revenue	2,197	2,555	4,907	4,535
Professional services | United Kingdom
Disaggregation of Revenue [Line Items]
Revenue	375	693	1,189	1,184
Professional services | Canada
Disaggregation of Revenue [Line Items]
Revenue	96	172	234	292
Professional services | Other International
Disaggregation of Revenue [Line Items]
Revenue	$ 457	$ 303	$ 575	$ 565