TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCE

9 Months Ended

Sep. 30, 2017

TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCE

6. TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCE

(in thousands)	September 30, 2017			December 31, 2016
Trade accounts receivable	$	164,530		$	234,473
Unbilled trade accounts receivable		32,820			34,681
Total trade accounts receivable		197,350			269,154
Allowance for sales credit memos		(6,189	)		(4,126	)
	$	191,161		$	265,028

Unbilled trade accounts receivable primarily relate to services earned under time and materials arrangements and to license, maintenance, and cloud arrangements that have commenced or been delivered in excess of scheduled invoicing.