Receivables (Schedule Of Allowance For Doubtful Accounts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Receivables [Abstract]
Balance at beginning of period	$ 1,307	$ 1,372	$ 1,132
Charged to costs and expenses	373	491	558
Amounts written off	(636)	(556)	(320)
Recoveries			2
Balance at end of period	$ 1,044	$ 1,307	$ 1,372