Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2011

Accounts, Notes, Loans and Financing Receivable, Gross, Allowance, and Net [Abstract]

Schedule of Accounts Receivable

Net accounts receivable consisted of the following (in thousands):

	December 31,
	2011			2010
Trade accounts receivable	$	142,166		$	116,212
Unbilled accounts	73,325			64,386
Gross accounts receivable	215,491			180,598
Allowance for doubtful accounts	(1,627		)	(1,329		)
Reserve for cash-basis customers	(2,928		)	(3,903		)
Total accounts receivable reserves	(4,555		)	(5,232		)
Accounts receivable, net	$	210,936		$	175,366