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		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Financial Instruments [Line Items]
Loans and other receivables	$ (10,564)	$ (5,294)	$ (24,901)	$ (2,377)
Financial Instruments Sold [Member]
Financial Instruments [Line Items]
Loans	407	110	405	238
Loan commitments	1,173	5,544	(2,573)	(1,622)
Long-term Debt [Member]
Financial Instruments [Line Items]
Loan commitments	(3,453)	0	(3,755)	0
Other changes in fair value	3,489	$ 0	10,305	$ 0
Principal Transactions Revenue [Member] | Long-term Debt [Member]
Financial Instruments [Line Items]
Other changes in fair value	3,900		10,700
Interest Expense [Member] | Long-term Debt [Member]
Financial Instruments [Line Items]
Other changes in fair value	$ 400		$ 400