Fair Value Measurement (Schedule Of Assumptions Used To Determine Fair Value) (Details)	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Dec. 31, 2011
Cumulative probability of earning maximum rate until maturity	0.00%
Liquidity risk premium	4.50%
Minimum [Member]
Cumulative probability of earning maximum rate until maturity		0.00%
Cumulative probability of principle returned prior to maturity	95.90%	95.40%
Cumulative probability of default at some future point	4.00%	1.30%
Liquidity risk premium		4.50%
Maximum [Member]
Cumulative probability of earning maximum rate until maturity		0.10%
Cumulative probability of principle returned prior to maturity	96.00%	98.70%
Cumulative probability of default at some future point	4.10%	4.60%
Liquidity risk premium		5.00%