Residential Mortgage Servicing Rights (Schedule Of Information Relates To Serviced Loan Portfolio) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Transfers and Servicing [Abstract]
Balance of loans serviced for others	$ 15,442,915	$ 15,336,597
MSR as a percentage of serviced loans	1.07%	1.00%