Accounts Receivable, Net

12 Months Ended

Dec. 31, 2017

Receivables [Abstract]

Accounts Receivable, Net

Note 2. Accounts Receivable, Net

Accounts receivable, net balances at December 31, 2017 and 2016 were as follows (in thousands):

	2017			2016
Trade accounts receivable	$	139,730		$	132,880
Unbilled revenue, at net realizable value		62,397			55,982
Total accounts receivable		202,127			188,862
Allowance for doubtful accounts		(13,827	)		(13,508	)
Accounts receivable, net	$	188,300		$	175,354

Changes in the allowance for doubtful accounts on accounts receivable are as follows (in thousands):

	2017			2016			2015
Balance at beginning of period	$	(13,508	)	$	(12,659	)	$	(11,915	)
Provision for losses		(5,529	)		(4,154	)		(5,804	)
Charge-offs, net of recoveries		5,210			3,305			5,060
Balance at end of period	$	(13,827	)	$	(13,508	)	$	(12,659	)