Segments Schedule of revenue by geographic region (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Geographic Areas, Revenues from External Customers [Abstract]
Total revenue	$ 49,652	$ 50,781	$ 44,759	$ 35,309	$ 48,880	$ 47,822	$ 42,686	$ 40,242	$ 180,501	$ 179,630	$ 165,989
Geographic Areas, Long-Lived Assets [Abstract]
Property and equipment, net	8,661				7,468				8,661	7,468		$ 5,751
United States
Geographic Areas, Revenues from External Customers [Abstract]
Total revenue									164,827	161,338	148,993
Geographic Areas, Long-Lived Assets [Abstract]
Property and equipment, net	6,364				6,265				6,364	6,265		4,621
International
Geographic Areas, Revenues from External Customers [Abstract]
Total revenue									15,674	18,292	$ 16,996
Geographic Areas, Long-Lived Assets [Abstract]
Property and equipment, net	$ 2,297				$ 1,203				$ 2,297	$ 1,203		$ 1,130