Introduction and Basis of Presentation (Tables)

12 Months Ended

Dec. 31, 2021

Changes in the allowance for doubtful accounts from December 31, 2018 to December 31, 2021 were as follows:

	Amount
	(in thousands)
Balance as of December 31, 2018	$	1,027
Addition (reduction) to credit loss expense		1,024
Write-offs, net of recoveries		(336	)
Balance as of December 31, 2019	$	1,715
Addition (reduction) to credit loss expense		1,712
Adjustments and write-offs, net of recoveries		(1,844	)
Balance as of December 31, 2020	$	1,583
Addition (reduction) to credit loss expense		1,210
Adjustments and write-offs, net of recoveries		(456	)
Balance as of December 31, 2021	$	2,337