UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended			9 Months Ended		12 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
OPERATING ACTIVITIES:
Net loss	$ (30,737)		$ (6,683)	$ (58,761)	$ (12,247)
Adjustments to reconcile net loss to net cash (used in) provided by operating activities:
Provision for bad debt		$ 6,300		6,445	590	$ 1,246
Depreciation and amortization	9,740		7,412	27,084	20,262
Stock-based compensation expense	1,149		1,055	3,439	3,577
Fair value changes in the contingent put option	(26,265)			(19,240)
Fair value changes in the compound embedded option	26,664			27,420
Fair value changes in business acquisitions contingent consideration	13,404		256	17,387	(670)
Fair value changes in the warrant options	9,311		2,510	9,312	4,059
Deferred income taxes				(1,563)	(1,308)
Cloud computing costs				(2,350)	(247)
Other				1,170	97
Changes in operating assets and liabilities—net of acquisitions:
Accounts receivable and contract assets				(7,736)	(2,732)
Prepaid expenses and other current assets				(1,349)	(179)
Accounts payable and other accrued liabilities				(4,829)	(95)
Accrued payroll and benefits				6,084	1,440
Payment of contingent consideration and other assumed purchase price obligations				(6,390)
Net cash (used in) provided by operating activities				(3,877)	12,547
INVESTING ACTIVITIES:
Purchases of property and equipment				(5,366)	(2,765)
Proprietary software development				(370)	(6)
Proceeds from net working capital adjustment related to acquisitions				2,819
Cash paid for acquisitions—net of cash acquired				(173,923)	(81,370)
Net cash used in investing activities				(176,840)	(84,141)
FINANCING ACTIVITIES:
Proceeds from line of credit				104,390	149,744
Payments on line of credit				(201,980)	(69,744)
Proceeds from term loans				175,000
Repayment of term loan				(49,297)
Payment of contingent consideration and other purchase price obligations				(6,004)	(1,136)
Repayment of capital leases				(2,257)	(1,304)
Proceeds from issuance of common stock in connection with initial public offering, net of issuance costs				161,288
Payments of deferred offering costs				(2,925)	(29)
Debt issuance costs				(4,866)	(417)
Debt extinguishment costs				(351)
Proceeds from issuance of common stock				171	139
Issuance of convertible and redeemable Series A-2 preferred stock and warrant				173,664
Redemption of the Series A-1 Preferred Stock				(131,821)
Dividend payment to the Series A-2 shareholders				(2,870)
Exercise of warrant options				25
Net cash provided by financing activities				212,167	77,253
CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH				31,450	5,659
Foreign exchange impact on cash balance				43	(5)
Beginning of year		$ 6,884		6,884	2,489	2,489
End of period	$ 38,377		$ 8,143	38,377	8,143	$ 6,884
SUPPLEMENTAL DISCLOSURES OF CASH FLOWS INFORMATION:
Cash paid for interest				9,368	2,689
Cash paid for income tax				171	878
SUPPLEMENTAL DISCLOSURES OF NON-CASH INVESTING AND FINANCING ACTIVITIES:
Series A-1 preferred stock deemed dividend—net of return from holders				24,341
Series A-1 preferred stock dividend paid in common shares				26,801
Accrued purchases of property and equipment				486	932
Property and equipment acquired under capital leases				1,753	2,757
Accretion of the redeemable series A-1 preferred stock to redeemable value				17,601	14,341
Common stock issued to acquire new businesses				25,000	4,047
Acquisitions unpaid contingent consideration				58,912	$ 5,401
Offering costs included in accounts payable and other accrued liabilities				$ 1,237