Mortgage Servicing Rights (Schedule Of Information Relates To Serviced Loan Portfolio) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Transfers and Servicing [Abstract]
Balance of loans serviced for others	$ 3,624,819	$ 3,162,080
MSR as a percentage of serviced loans	0.89%	0.87%