REVENUE RECOGNITION (Tables)

12 Months Ended

Dec. 31, 2021

Revenue from Contract with Customer [Abstract]

Disaggregation of Revenue

The approximate percentage of net revenue by type of customer was as follows:

	Year Ended December 31,
	2021		2020		2019
Healthcare insurers:
Fee-for-service	39	%	34	%	33	%
Capitated	3		3		3
Total healthcare insurers	42		37		36
Government payers	10		11		15
Client payers	33		38		32
Patients	12		11		13
Total DIS	97		97		96
DS	3		3		4
Net revenues	100	%	100	%	100	%

Accounts Receivable Disaggregation

The approximate percentage of net accounts receivable by type of customer as of December 31, 2021 and 2020 was as follows:

	2021	2020
Healthcare insurers	32%	34%
Government payers	6	6
Client payers	38	46
Patients (including coinsurance and deductible responsibilities)	21	11
Total DIS	97	97
DS	3	3
Net accounts receivable	100%	100%

Accounts Receivable, Allowance for Credit Loss

The following table summarizes the activity for the Company's allowance for credit losses during the years ended December 31, 2021 and 2020, which principally relates to client payers:

	Allowance for Credit Losses
Balance, January 1, 2020	$	15
Provision for credit losses	19
Write-offs of accounts receivable, net of recoveries	(6)
Balance, December 31, 2020	28
Provision for credit losses	4
Write-offs of accounts receivable, net of recoveries	(1)
Balance, December 31, 2021	$	31