Basis of presentation and description of business - Consolidated Statement of Cash Flows (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		Jun. 30, 2020		Dec. 31, 2020		Dec. 31, 2019		Dec. 31, 2018
Cash flows from operating activities
Net income (loss)	$ (16,467)	[1]	$ (4,589)		$ (834)	[1]	$ (21,056)	[1],[2]	$ (10,330)	[1]	$ (24,082)		$ (34,345)		$ (37,579)
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization expense			9,784				19,538	[2]	19,170	[1]	38,511		37,082		33,962
Amortization of deferred contract costs			2,700				5,861	[2]	3,452	[1]	7,953		5,236		2,864
Amortization of debt issuance costs			69				249	[2]	571	[1]	773		1,120		513
Non-cash lease expense			1,267				2,398	[2]	0	[1]
Provision for bad debt expense and returns			159				(41)	[2]	812	[1]	1,024		279		37
Loss on disposal of equipment and leasehold improvements									0		0		0		0
Loss on extinguishment of debt											5,213
Share‑based compensation			2,832				6,938	[2]	1,575	[1]	6,743		2,461		2,315
Deferred tax benefit			(613)				(669)	[2]	(3,082)	[1]	(10,318)		(11,169)		(12,379)
Adjustment to contingent consideration			300				4,237	[2]	(3,700)	[1]	(1,000)		200
Other			201				454	[2]	(156)	[1]	(490)		292		(34)
Changes in operating assets and liabilities:
Trade accounts receivable			(7,066)				2,249	[2]	(7,316)	[1]	(23,112)		(14,799)		(3,353)
Income tax receivable/payable			376				(238)	[2]	(278)	[1]	(766)		559		(977)
Prepaid expenses and other assets			(3,317)				(2,986)	[2]	928	[1]	(3,620)		(5,106)		(2,557)
Deferred contract costs			(5,065)				(11,848)	[2]	(8,035)	[1]	(20,398)		(14,045)		(10,940)
Deferred taxes											0
Accounts payable			(1,191)				2,284	[2]	202	[1]	4,026		1,000		(313)
Accrued liabilities			(7,683)				(1,889)	[2]	(2,371)	[1]	5,501		6,349		6,001
Deferred revenue			15,913				32,627	[2]	16,833	[1]	64,945		37,374		31,839
Other liabilities			(54)				(86)	[2]	1,240	[1]	1,898		(58)		(39)
Net cash provided by operating activities			4,023				38,022	[2]	9,515	[1]	52,801		11,846		9,360
Cash flows from investing activities
Acquisition, net of cash acquired			(3,041)				(3,041)	[2]	0	[1]	(2,512)		(40,173)		(2,893)
Purchases of equipment and leasehold improvements			(3,290)				(5,211)	[2]	(1,366)	[1]	(4,368)		(7,190)		(2,909)
Proceeds from sale of equipment and leasehold improvements			12				22	[2]	0	[1]	4
Net cash used in investing activities			(6,319)				(8,230)	[2]	(1,366)	[1]	(6,876)		(47,363)		(5,802)
Cash flows from financing activities
Proceeds from debt													40,000
Debt issuance costs							(530)	[2]	0	[1]	(1,264)		(1,550)
Payment of debt											(205,000)		(10,000)
Payment of debt extinguishment costs											(2,050)
Proceeds from Issuance Initial Public Offering											326,316
Cash paid for offering costs							(243)	[2]	(2,203)	[1]	(7,256)		(721)
Proceeds from private placement											2,233
Proceeds from the exercise of stock options			4,019				7,063	[2]	103	[1]	2,985		923		1,770
Net cash provided by (used in) financing activities			4,019				2,084	[2]	(2,100)	[1]	115,964		28,652		1,770
Effect of exchange rate changes on cash and cash equivalents			(401)				(259)	[2]	0	[1]	604
Net increase in cash and cash equivalents			1,322				31,617	[2]	6,049	[1]	162,493		(6,865)		5,328
Cash and cash equivalents, beginning of period	196,190		194,868	[1],[2]			194,868	[1],[2]	32,375	[1]	32,375	[1]	39,240		33,912
Cash and cash equivalents, end of period	226,485	[2]	196,190		38,424	[1]	226,485	[2]	38,424	[1]	194,868	[1],[2]	32,375	[1]	39,240
Supplemental disclosures of cash flow information:
Cash paid for interest			3				6	[2]	9,262	[1]	12,649		20,693		17,835
Cash paid for income taxes, net of refunds			351				832	[2]	411	[1]	1,394		596		1,461
Offering costs accrued but not paid			(19)				300	[2]	2,865	[1]
Non-cash investing activities:
Leasehold improvements acquired through lease incentives													2,672		369
As Previously Reported
Cash flows from operating activities
Net income (loss)			(3,069)		(423)				(8,713)		(22,771)		(32,600)		(36,256)
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization expense			9,784						19,002		38,168		36,807		33,914
Amortization of deferred contract costs			3,296						4,218		9,647		6,250		3,391
Amortization of debt issuance costs			69						571		773		1,120		513
Non-cash lease expense			1,267
Provision for bad debt expense and returns			159						812		1,024		279		37
Loss on disposal of equipment and leasehold improvements									(12)		(29)		(17)		14
Loss on extinguishment of debt											5,213
Share‑based compensation			2,832						1,575		6,743		2,461		2,315
Deferred tax benefit			(758)						(3,217)		(8,675)		(11,247)		(12,550)
Adjustment to contingent consideration			300						(3,700)		(1,000)		200
Other			62						0		(263)		0		0
Changes in operating assets and liabilities:
Trade accounts receivable			(7,066)						(7,374)		(23,170)		(14,741)		(3,353)
Income tax receivable/payable			463						(278)		(766)		559		(977)
Prepaid expenses and other assets			(3,317)						429		(4,119)		(4,585)		(2,555)
Deferred contract costs			(6,496)						(10,035)		(24,589)		(17,050)		(13,222)
Deferred taxes											145
Accounts payable			(1,191)						258		3,888		1,138		(313)
Accrued liabilities			(7,694)						(2,371)		5,501		6,390		5,965
Deferred revenue			15,472						17,028		65,125		36,998		32,476
Other liabilities			(90)						1,240		1,898		(58)		(39)
Net cash provided by operating activities			4,023						9,457		52,743		11,904		9,360
Cash flows from investing activities
Acquisition, net of cash acquired			(3,041)								(2,512)		(40,173)		(2,893)
Purchases of equipment and leasehold improvements			(3,290)						(1,366)		(4,368)		(7,190)		(2,909)
Proceeds from sale of equipment and leasehold improvements			12								4
Net cash used in investing activities			(6,319)						(1,366)		(6,876)		(47,363)		(5,802)
Cash flows from financing activities
Proceeds from debt													40,000
Debt issuance costs											(1,264)		(1,550)
Payment of debt											(205,000)		(10,000)
Payment of debt extinguishment costs											(2,050)
Proceeds from Issuance Initial Public Offering											326,316
Cash paid for offering costs									(2,203)		(7,256)		(721)
Proceeds from private placement											2,233
Proceeds from the exercise of stock options			4,019						103		2,985		923		1,770
Net cash provided by (used in) financing activities			4,019						(2,100)		115,964		28,652		1,770
Effect of exchange rate changes on cash and cash equivalents			(401)						0		604
Net increase in cash and cash equivalents			1,322						5,991		162,435		(6,807)		5,328
Cash and cash equivalents, beginning of period	196,190		194,868				194,868		32,433		32,433		39,240		33,912
Cash and cash equivalents, end of period			196,190		38,424				38,424		194,868		32,433		39,240
Supplemental disclosures of cash flow information:
Cash paid for interest			3						9,262		12,649		20,693		17,835
Cash paid for income taxes, net of refunds			351						411		1,394		596		1,461
Offering costs accrued but not paid			(19)						2,865
Non-cash investing activities:
Leasehold improvements acquired through lease incentives													0		0
Adjustments | Commissions
Cash flows from operating activities
Net income (loss)			(905)		(402)				(923)		(1,878)		(1,503)		(1,327)
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization expense			0						0		0		0		0
Amortization of deferred contract costs			(596)						(766)		(1,694)		(1,014)		(527)
Amortization of debt issuance costs			0						0		0		0		0
Non-cash lease expense			0
Provision for bad debt expense and returns			0						0		0		0		0
Loss on disposal of equipment and leasehold improvements									0		0		0		0
Loss on extinguishment of debt											0
Share‑based compensation			0						0		0		0		0
Deferred tax benefit			70						(311)		(619)		(488)		(428)
Adjustment to contingent consideration			0						0		0		0
Other			0						0		0		0		0
Changes in operating assets and liabilities:
Trade accounts receivable			0						0		0		0		0
Income tax receivable/payable			0						0		0		0		0
Prepaid expenses and other assets			0						0		0		0		0
Deferred contract costs			1,431						2,000		4,191		3,005		2,282
Deferred taxes											0
Accounts payable			0						0		0		0		0
Accrued liabilities			0						0		0		0		0
Deferred revenue			0						0		0		0		0
Other liabilities			0						0		0		0		0
Net cash provided by operating activities			0						0		0		0		0
Cash flows from investing activities
Acquisition, net of cash acquired			0								0		0		0
Purchases of equipment and leasehold improvements			0						0		0		0		0
Proceeds from sale of equipment and leasehold improvements			0								0
Net cash used in investing activities			0						0		0		0		0
Cash flows from financing activities
Proceeds from debt													0
Debt issuance costs											0		0
Payment of debt											0		0
Payment of debt extinguishment costs											0
Proceeds from Issuance Initial Public Offering											0
Cash paid for offering costs									0		0		0
Proceeds from private placement											0
Proceeds from the exercise of stock options			0						0		0		0		0
Net cash provided by (used in) financing activities			0						0		0		0		0
Effect of exchange rate changes on cash and cash equivalents									0		0
Net increase in cash and cash equivalents			0						0		0		0		0
Cash and cash equivalents, beginning of period	0		0				0		0		0		0		0
Cash and cash equivalents, end of period			0		0				0		0		0		0
Supplemental disclosures of cash flow information:
Cash paid for interest			0						0		0		0		0
Cash paid for income taxes, net of refunds			0						0		0		0		0
Offering costs accrued but not paid			0						0
Non-cash investing activities:
Leasehold improvements acquired through lease incentives													0		0
Adjustments | Other
Cash flows from operating activities
Net income (loss)			(615)		(9)				(694)		567		(242)		4
Adjustments to reconcile net loss to cash provided by operating activities:
Depreciation and amortization expense			0						168		343		275		48
Amortization of deferred contract costs			0						0		0		0		0
Amortization of debt issuance costs			0						0		0		0		0
Non-cash lease expense			0
Provision for bad debt expense and returns			0						0		0		0		0
Loss on disposal of equipment and leasehold improvements									12		29		17		(14)
Loss on extinguishment of debt											0
Share‑based compensation			0						0		0		0		0
Deferred tax benefit			75						446		(1,024)		566		599
Adjustment to contingent consideration			0						0		0		0
Other			139						(156)		(227)		292		(34)
Changes in operating assets and liabilities:
Trade accounts receivable			0						58		58		(58)		0
Income tax receivable/payable			(87)						0		0		0		0
Prepaid expenses and other assets			0						499		499		(521)		(2)
Deferred contract costs			0						0		0		0		0
Deferred taxes											(145)
Accounts payable			0						(56)		138		(138)		0
Accrued liabilities			11						0		0		(41)		36
Deferred revenue			441						(195)		(180)		376		(637)
Other liabilities			36						0		0		0		0
Net cash provided by operating activities			0						58		58		(58)		0
Cash flows from investing activities
Acquisition, net of cash acquired			0								0		0		0
Purchases of equipment and leasehold improvements			0						0		0		0		0
Proceeds from sale of equipment and leasehold improvements			0								0
Net cash used in investing activities			0						0		0		0		0
Cash flows from financing activities
Proceeds from debt													0
Debt issuance costs											0		0
Payment of debt											0		0
Payment of debt extinguishment costs											0
Proceeds from Issuance Initial Public Offering											0
Cash paid for offering costs									0		0		0
Proceeds from private placement											0
Proceeds from the exercise of stock options			0						0		0		0		0
Net cash provided by (used in) financing activities			0						0		0		0		0
Effect of exchange rate changes on cash and cash equivalents									0		0
Net increase in cash and cash equivalents			0						58		58		(58)		0
Cash and cash equivalents, beginning of period	$ 0		0				$ 0		(58)		(58)		0		0
Cash and cash equivalents, end of period			0		$ 0				0		0		(58)		0
Supplemental disclosures of cash flow information:
Cash paid for interest			0						0		0		0		0
Cash paid for income taxes, net of refunds			0						0		$ 0		0		0
Offering costs accrued but not paid			$ 0						$ 0
Non-cash investing activities:
Leasehold improvements acquired through lease incentives													$ 2,672		$ 369

[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.