Accounts Receivable (Tables)

12 Months Ended

Dec. 31, 2013

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

Schedule of Accounts Receivable

Net accounts receivable consisted of the following as of December 31, 2013 and 2012 (in thousands):

	December 31, 2013			December 31, 2012
Trade accounts receivable	$	175,391		$	143,533
Unbilled accounts	100,300			79,051
Gross accounts receivable	275,691			222,584
Allowance for doubtful accounts	(708		)	(1,154		)
Reserve for cash-basis customers	(2,995		)	(2,653		)
Total accounts receivable reserves	(3,703		)	(3,807		)
Accounts receivable, net	$	271,988		$	218,777

Schedule of Activity in the Accounts Receivable Reserves

A summary of activity in the accounts receivable reserves for the years ended December 31, 2013, 2012 and 2011, is as follows (in thousands):

	2013			2012			2011
Beginning balance	$	3,807		$	4,555		$	5,232
Charges to income from operations	17,900			15,599			16,165
Write-offs	(486		)	(47		)	(420		)
Collections from cash basis customers	(17,518		)	(16,300		)	(16,422		)
Ending balance	$	3,703		$	3,807		$	4,555