Fair Values Of Assets and Liabilities (Schedule Of Valuation Techniques And Significant Unobservable Inputs Used To Measure Both Recurring And Non-Recurring) (Detail) - USD ($) $ in Thousands		3 Months Ended	9 Months Ended
		Sep. 30, 2015	Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		$ 2,214,281	$ 2,214,281	$ 1,792,078	$ 1,782,648
Impaired loans—collateral based	[1]	$ 113,027	113,027	127,412	129,537
Other Real Estate Owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		$ 297,342	297,342	238,529	187,103
Equity securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		54,004	54,004	51,139	52,155
Fair Value, Measurements, Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Mortgage servicing rights		7,875	7,875	8,435	8,137
Fair Value, Measurements, Recurring | Municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		297,342	297,342	238,529	187,103
Fair Value, Measurements, Recurring | Equity securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		54,004	54,004	51,139	52,155
Fair Value, Measurements, Nonrecurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans—collateral based		73,819	73,819
Other real estate owned	[2]	80,524	80,524
Level 3 | Fair Value, Measurements, Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Mortgage servicing rights		$ 7,875	7,875	8,435	8,137
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Methodology		Discounted cash flows
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate		9.00%
Fair Value Inputs, Prepayment Rate		9.00%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate		13.00%
Fair Value Inputs, Prepayment Rate		29.00%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Discount Rate Input
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Input		Discount rate
Range of Inputs		9%-13%
Weighted Average of Inputs		9.15%
Impact to valuation from an increased or higher input value		Decrease
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Prepayment Rate Input
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Significant Unobservable Input		Constant prepayment rate (CPR)
Range of Inputs		9%-29%
Weighted Average of Inputs		12.93%
Impact to valuation from an increased or higher input value		Decrease
Level 3 | Fair Value, Measurements, Recurring | Municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		$ 68,401	68,401	58,953	50,237
Valuation Methodology		Bond pricing
Significant Unobservable Input		Equivalent rating
Range of Inputs		BBB-AA+
Impact to valuation from an increased or higher input value		Increase
Level 3 | Fair Value, Measurements, Recurring | Equity securities
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities, at fair value		$ 24,516	$ 24,516	$ 23,711	$ 23,961
Valuation Methodology		Discounted cash flows
Significant Unobservable Input		Discount rate
Range of Inputs		2.01%-2.43%
Weighted Average of Inputs		2.22%
Impact to valuation from an increased or higher input value		Decrease
Level 3 | Fair Value, Measurements, Recurring | Equity securities | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate		2.01%
Level 3 | Fair Value, Measurements, Recurring | Equity securities | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate		2.43%	2.43%
Level 3 | Fair Value, Measurements, Nonrecurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans—collateral based		$ 73,819	$ 73,819
Other real estate owned		$ 80,524	$ 80,524
Level 3 | Fair Value, Measurements, Nonrecurring | Impaired Loans
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Methodology		Appraisal value
Significant Unobservable Input		Appraisal adjustment - cost of sale
Range of Inputs		10%
Weighted Average of Inputs		10.00%
Impact to valuation from an increased or higher input value		Decrease
Level 3 | Fair Value, Measurements, Nonrecurring | Impaired Loans | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Level 3 | Fair Value, Measurements, Nonrecurring | Impaired Loans | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Level 3 | Fair Value, Measurements, Nonrecurring | Other Real Estate Owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Methodology		Appraisal value
Significant Unobservable Input		Appraisal adjustment - cost of sale
Range of Inputs		10%
Weighted Average of Inputs		10.00%
Impact to valuation from an increased or higher input value		Decrease
Level 3 | Fair Value, Measurements, Nonrecurring | Other Real Estate Owned | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Level 3 | Fair Value, Measurements, Nonrecurring | Other Real Estate Owned | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%

[1] Impaired loans are considered by the Company to be non-accrual loans, TDRs or loans with principal and/or interest at risk, even if the loan is current with all payments of principal and interest.

[2] Fair value losses recognized, net on other real estate owned include valuation adjustments and charge-offs during the respective period.