Fair Value Measurements Fair Value Measurments (Quantitative Information about Unobservable Inputs) (Details)	9 Months Ended
	Aug. 31, 2013
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Liquidity risk premium	4.00%
Market credit default swap spread	4.05%
Credit rating of insurer (in credit rating)	AA-
Minimum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Probability of earning maximum rate until maturity	0.20%
Probability of principal returned prior to maturity	75.70%
Probability of default	4.10%
Recovery rate in default	50.00%
Maximum [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Probability of earning maximum rate until maturity	9.90%
Probability of principal returned prior to maturity	95.10%
Probability of default	24.10%
Recovery rate in default	70.00%
Weighted Average [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Probability of earning maximum rate until maturity	1.70%
Probability of principal returned prior to maturity	87.00%
Probability of default	11.30%
Recovery rate in default	56.50%