Accounting For Income Taxes (Schedule Of Components Of Income Tax Expense) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accounting For Income Taxes [Abstract]
Taxes currently provided	$ 32,625	$ 13,423	$ 32,470
Deferred income tax expense	24,007	37,734	13,853
Total income tax expense	$ 56,632	$ 51,157	$ 46,323