TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCE

3 Months Ended

Mar. 31, 2014

TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCE

5.    TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCE

(in thousands)	March 31,             2014		December 31,             2013
Trade accounts receivable	$	80,084	$	129,007
Unbilled trade accounts receivable		30,329		38,618
Total accounts receivable		110,413		167,625
Allowance for sales credit memos		(1,762)		(1,997)
	$	108,651	$	165,628

Unbilled trade accounts receivable relate to services earned under time and material arrangements, and maintenance and license arrangements that had not been invoiced as of March 31, 2014 and December 31, 2013, respectively.