Accounts Receivable

12 Months Ended

Dec. 31, 2020

Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]

Accounts Receivable

Accounts Receivable

Net accounts receivable consisted of the following as of December 31, 2020 and 2019 (in thousands):

	December 31, 2020		December 31, 2019
Trade accounts receivable	$	473,474	$	396,204
Unbilled accounts receivable	188,400		157,619
Gross accounts receivable	661,874		553,823
Allowance for current expected credit losses and other reserves	(1,822)		(1,880)
Accounts receivable, net	$	660,052	$	551,943

A summary of activity in the accounts receivable allowance for current expected credit losses and other reserves for the years ended December 31, 2020, 2019 and 2018 is as follows (in thousands):

	2020		2019		2018
Beginning balance	$	1,880	$	1,534	$	1,281
Charges to income from operations	12,347		5,116		3,824
Collections from customers previously reserved and other	(12,405)		(4,770)		(3,571)
Ending balance	$	1,822	$	1,880	$	1,534

Charges to income from operations primarily represents charges to bad debt expense for increases in the allowance for current expected credit losses.