Summary Of Significant Accounting Policies (Summary Of Adjustments In Allowances For Doubtful Accounts And Sales Adjustments) (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]
Balance at beginning of year	$ 1,603	$ 2,389	$ 2,115
Provisions for losses - accounts receivable	805	1,161	1,538
Collection of accounts previously reserved	(142)	4
Deductions for accounts charged off or credits issued	(1,276)	(1,951)	(1,264)
Balance at end of year	$ 990	$ 1,603	$ 2,389