Trade Accounts Receivable, Net Of Allowances

6 Months Ended

Jun. 30, 2011

Trade Accounts Receivable, Net Of Allowances

Trade Accounts Receivable, Net Of Allowances

5.    TRADE ACCOUNTS RECEIVABLE, NET OF ALLOWANCES

(in thousands)	June 30, 2011		December 31, 2010
Trade accounts receivable	$	75,742	$	65,373
Unbilled accounts receivable		22,114		15,682
Total accounts receivable		97,856		81,055
Allowance for doubtful accounts		(136)		(132)
Allowance for sales credit memos		(1,221)		(1,027)
Total allowance		(1,357)		(1,159)
	$	96,499	$	79,896

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 June 30, 2011 and December 31, 2010, respectively.