Financial Instruments (Schedule Of Significant Inputs And Assumptions Used To Determine Fair Value Of Available-For-Sale Securities) (Details)	3 Months Ended
	Jun. 30, 2012	Dec. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]
Discount rate for periodic interest payment	1.07%	1.13%
Discount rate for principle repayment	1.66%	1.93%
Liquidity discount	0.90%	0.90%
Credit discounts	2.00%	2.00%
Estimated period (years)	17	17