Receivables (Schedule Of Trade Accounts Receivables Net) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Receivables [Abstract]
Accounts receivable - trade	$ 239,033	$ 172,857
Allowance for doubtful accounts	(1,044)	(1,307)	(1,372)	(1,132)
Accounts receivable - trade, net	$ 237,989	$ 171,550