Assets (Details 2) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 143,009,000	$ 163,493,000
Less allowance for doubtful accounts	(651,000)	(2,757,000)
Accounts receivable, net	142,358,000	160,736,000
Reference rate	LIBOR
Percentage points added to reference rate	5.00%
Allowance for Doubtful Accounts Receivable [Roll Forward]
Balance at beginning of period	2,757,000	2,519,000	1,167,000
Bad debt expense	377,000	1,921,000	1,549,000
Write-offs, net of recoveries	(2,483,000)	(1,683,000)	(197,000)
Balance at end of period	651,000	2,757,000	2,519,000
Proceeds from sale of accounts receivable	186,600,000	59,900,000	3,000,000
Loss on sale of accounts receivable	500,000	300,000	0
Trade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	96,535,000	113,382,000
Other
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	11,445,000	17,554,000
Unbilled
Accounts, Notes, Loans and Financing Receivable [Line Items]
Accounts receivable, gross	$ 35,029,000	$ 32,557,000