Accounts Receivable (Details) (USD $) In Thousands	Sep. 30, 2011	Dec. 31, 2010
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 148,360	$ 135,304
Less: Allowance for doubtful accounts	(2,878)	(3,079)
Accounts receivable, net	145,482	132,225
Accounts receivable - trade
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	133,199	118,265
Accounts receivable - grants
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total accounts receivable	$ 15,161	$ 17,039