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	9 Months Ended
	Sep. 30, 2016	Dec. 31, 2015	Sep. 30, 2015
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	$ 1,650,096	$ 1,716,388	$ 2,214,281
Impaired loans—collateral based	$ 90,540	101,255	113,027
Other Real Estate Owned
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount for lack of market	10.00%
Municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	$ 109,281	108,595	297,342
Fair Value, Measurements, Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
MSRs	13,901	9,092	7,875
Fair Value, Measurements, Recurring | Municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	109,281	108,595	297,342
Fair Value, Measurements, Nonrecurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans—collateral based	64,614
Other real estate owned	45,449
Level 3 | Fair Value, Measurements, Recurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
MSRs	$ 13,901	9,092	7,875
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate	5.52%
Fair Value Inputs, Prepayment Rate	14.73%
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	3.00%
Fair Value Inputs, Prepayment Rate	2.00%
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	7.00%
Fair Value Inputs, Prepayment Rate	85.00%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Discount Rate Input
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Valuation Methodology	Discounted cash flows
Significant Unobservable Input	Discount rate
Range of Inputs	3%-7%
Impact to valuation from an increased or higher input value	Decrease
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Discount Rate Input | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate	5.52%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Discount Rate Input | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate	3.00%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Discount Rate Input | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Discount Rate	7.00%
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	2%-85%
Impact to valuation from an increased or higher input value	Decrease
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Prepayment Rate Input | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Prepayment Rate	14.73%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Prepayment Rate Input | Minimum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Prepayment Rate	2.00%
Level 3 | Fair Value, Measurements, Recurring | Mortgage Servicing Rights Prepayment Rate Input | Maximum
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Fair Value Inputs, Prepayment Rate	85.00%
Level 3 | Fair Value, Measurements, Recurring | Municipal
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Available-for-sale securities	$ 67,208	$ 68,613	$ 68,401
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, Nonrecurring
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Impaired loans—collateral based	$ 64,614
Other real estate owned	$ 45,449
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
Discount for lack of market	10.00%
Impact to valuation from an increased or higher input value	Decrease
Level 3 | Fair Value, Measurements, Nonrecurring | Impaired Loans | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount for lack of market	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
Discount for lack of market	10.00%
Impact to valuation from an increased or higher input value	Decrease
Level 3 | Fair Value, Measurements, Nonrecurring | Other Real Estate Owned | Weighted Average
Fair Value Measurements, Recurring and Nonrecurring, Valuation Techniques [Line Items]
Discount for lack of market	10.00%