Summary Of Significant Accounting Policies (Schedule Of Allowance For Uncollectible Accounts) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Summary Of Significant Accounting Policies [Abstract]
Allowances, beginning of year	$ 17	$ 1,338	$ 1,304
Amounts charged to expense	865	(48)	285
Write-offs of uncollectible receivables	(243)	(1,273)	(251)
Allowances, end of year	639	17	1,338
Notes receivable	$ 20,742