Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2018

Accounts Receivable

Schedule of components of accounts receivables

December 31,	2018			2017
(in thousands)
Trade receivables:
Billed	$	266,660		$	296,588
Unbilled		56,408			68,494
Other receivables		5,278			17,242
Total		328,346			382,324
Less: allowance for doubtful accounts		(4,813	)		(4,471	)
Accounts receivable, net	$	323,533		$	377,853

Schedule of changes in allowance for doubtful accounts

Years Ended December 31,	2018			2017
(in thousands)
Beginning balance	$	4,471		$	2,553
Bad debt expense		588			1,441
Accounts written-off		(260	)		(105	)
Recoveries		14			582
Ending balance	$	4,813		$	4,471