Basis of presentation and description of business - Basis of Presentation and Revision Narrative (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended				12 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020		Jun. 30, 2021	[2]	Jun. 30, 2020		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Business Acquisition [Line Items]
Revenue	$ 86,238	$ 80,727	$ 62,264	[1]	$ 166,965		$ 122,317	[1]	$ 269,132	$ 203,965	$ 147,384
Sales and marketing	32,617	30,167	20,781	[1]	62,784		43,785	[1]	98,885	73,103	53,749
Subscription
Business Acquisition [Line Items]
Revenue	$ 80,718	74,482	58,600	[1]	$ 155,200		112,804	[1]	248,879	175,118	113,867
Adjustments | Error in Commissions Capitalized
Business Acquisition [Line Items]
Sales and marketing		800							2,500	2,000	1,800
Deferred contract costs		$ (800)							$ (2,500)	$ (2,000)	$ (1,800)
Adjustments | Subscription | Classification of on Premise Subscription Revenue
Business Acquisition [Line Items]
Revenue			$ 5,800				$ 10,300

[1] Certain prior period amounts have been revised to correct immaterial errors. See Note 1 for more information.

[2] Includes the three months ended March 31, 2021, which has been revised to correct immaterial errors. See Note 1 for more information.