Fair Value Measurements (Summary Of Changes In Fair Value Of Level 3 Financial Assets And Financial Liabilities Held At Fair Value) (Details) - Partnership Interest in a Private Credit Fund [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 9,068	$ 10,431
Net realized gains (losses) included in earnings	691	(1,363)
Purchases	1,481	0
Sales	(9,759)	0
Ending Balance	1,481	9,068
The amount of total gains (losses) for the period included in earnings attributable to assets still held at December 31	$ 0	$ (1,363)