Accounts Receivable (Details) (USD $) In Thousands	Jun. 30, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 156,310	$ 135,304
Less: Allowance for doubtful accounts	(2,979)	(3,079)
Accounts receivable, net	153,331	132,225
Accounts receivable - trade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	139,033	118,265
Accounts receivable - grants
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 17,277	$ 17,039