Fair Values Of Assets And Liabilities (Narrative) (Detail) - USD ($)		3 Months Ended
		Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		$ 770,983,000	$ 1,716,388,000	$ 1,721,030,000
Mortgage loans held-for-sale		314,554,000	388,038,000	446,355,000
Impaired loans—collateral based	[1]	$ 96,110,000	101,255,000	112,404,000
Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Estimate of Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		$ 770,983,000	1,716,388,000	1,721,030,000
Mortgage servicing rights		10,128,000	9,092,000	7,852,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale		299,000,000	372,000,000	421,200,000
Mortgage loans held-for-sale		314,554,000	388,038,000	446,355,000
Impaired loans—collateral based		66,000,000
Portion at Other than Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based		30,100,000
Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		121,195,000	108,595,000	269,912,000
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		55,619,000	56,686,000	54,446,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights		10,128,000	9,092,000	7,852,000
Mortgage loans held-for-sale		314,554,000	388,038,000	446,355,000
Fair Value, Measurements, Recurring | Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		121,195,000	108,595,000	269,912,000
Fair Value, Measurements, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		55,619,000	56,686,000	54,446,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based		66,008,000
Other real estate owned	[2]	58,978,000
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights		10,128,000	9,092,000	7,852,000
Mortgage loans held-for-sale		$ 0	0	0
Level 3 | Fair Value, Measurements, Recurring | Minimum | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount Rate		4.00%
Fair Value Inputs, Prepayment Rate		1.00%
Level 3 | Fair Value, Measurements, Recurring | Maximum | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount Rate		7.00%
Fair Value Inputs, Prepayment Rate		46.00%
Level 3 | Fair Value, Measurements, Recurring | Weighted Average | Mortgage Servicing Rights
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount Rate		6.20%
Fair Value Inputs, Prepayment Rate		11.39%
Level 3 | Fair Value, Measurements, Recurring | Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		$ 70,242,000	68,613,000	56,049,000
Level 3 | Fair Value, Measurements, Recurring | Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value		$ 24,054,000	25,199,000	24,656,000
Level 3 | Fair Value, Measurements, Recurring | Equity securities | Minimum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount Rate		2.81%
Level 3 | Fair Value, Measurements, Recurring | Equity securities | Maximum
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount Rate		3.13%
Level 3 | Fair Value, Measurements, Recurring | Equity securities | Weighted Average
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount Rate		2.98%
Level 3 | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based		$ 66,008,000
Other real estate owned		$ 58,978,000
Level 3 | Fair Value, Measurements, Nonrecurring | Minimum | Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Level 3 | Fair Value, Measurements, Nonrecurring | Maximum | Other Real Estate Owned
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value Inputs, Discount for Lack of Marketability		10.00%
Non-performing
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans held-for-sale		$ 0	$ 0	$ 0

[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.