Receivables (Details) (USD $)	3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables	$ 252,661,000	$ 254,036,000
Allowance for doubtful accounts receivable	(1,752,000)	(767,000)
Net receivables	250,909,000	253,269,000
Bad debt expense	1,100,000
Accounts receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables	249,545,000	252,413,000
Notes receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables	63,000	0
Other receivables [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Gross receivables	$ 3,053,000	$ 1,623,000