Fair Value Disclosures (Summary Of Gains (Losses) Due To Changes In Instrument Specific Credit Risk For Loans and Other Receivables And Loan Commitments Measured At Fair Value Under Fair Value Option) (Details) - USD ($) $ in Thousands	3 Months Ended
	Feb. 28, 2019	Mar. 31, 2018
Financial Instruments [Line Items]
Loans and other receivables	$ (7,335)	$ 2,628
Trading Liabilities
Financial Instruments [Line Items]
Loans	0	250
Loan commitments	79	(129)
Long-term debt
Financial Instruments [Line Items]
Changes in instrument specific credit risk	23,483	(16,202)
Other changes in fair value	$ (10,643)	$ 41,154