Valuation And Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Allowance For Doubtful Receivables [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	$ 3,134	$ 3,220	$ 2,925
Charged to Costs and Expenses	6,593	6,636	6,403
Adjustments/Amounts Written Off	(6,858)	(6,722)	(6,108)
Balance at End of Year	2,869	3,134	3,220
Deferred Tax Asset Valuation Allowance [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at Beginning of Year	12,750	10,195	10,176
Charged to Costs and Expenses
Adjustments/Amounts Written Off	435	2,555	19
Balance at End of Year	$ 13,185	$ 12,750	$ 10,195