Fair Values Of Assets And Liabilities (Summary Of Changes In Level 3 Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Municipal Bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	$ 30,770		$ 24,211
Total net gains (losses) included in Net income
Total net gains (losses) included in Other comprehensive income	(12)		2
Purchases	1,687		3,840
issuances
Sales
Settlements	(121)		(116)
Net transfers into Level 3			(2,402)	[1]
Ending Balance	32,324		25,535
Equity Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	22,169		18,971
Total net gains (losses) included in Net income
Total net gains (losses) included in Other comprehensive income	2,301		2,253
Purchases
issuances
Sales
Settlements
Net transfers into Level 3
Ending Balance	24,470		21,224
Mortgage Servicing Rights [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning Balance	6,750		6,700
Total net gains (losses) included in Net income	594	[2]	501	[2]
Total net gains (losses) included in Other comprehensive income
Purchases
issuances
Sales
Settlements
Net transfers into Level 3
Ending Balance	$ 7,344		$ 7,201

[1] During the first quarter of 2012, one municipal security was transferred out of Level 3 into Level 2 as observable market information was available that market participants would use in pricing these securities. Transfers out of Level 3 are recognized at the end of the reporting period.

[2] Changes in the balance of mortgage servicing rights are recorded as a component of mortgage banking revenue in non-interest income.