Fair Values Of Assets And Liabilities (Narrative) (Detail) - USD ($)	6 Months Ended
	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	$ 637,663,000	$ 1,716,388,000	$ 2,162,061,000
Mortgage loans held-for-sale	554,256,000	388,038,000	497,283,000
Impaired loans—collateral based	$ 95,976,000	101,255,000	103,357,000
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	$ 637,663,000	1,716,388,000	2,162,061,000
MSRs	13,382,000	9,092,000	8,034,000
Remaining contractual principal balance outstanding, mortgage loans held-for-sale	529,000,000	372,000,000	475,900,000
Mortgage loans held-for-sale	554,256,000	388,038,000	497,283,000
Impaired loans—collateral based	67,800,000
Portion at Other than Fair Value Measurement
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	28,100,000
Municipal
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	111,640,000	108,595,000	269,790,000
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale securities, at fair value	56,579,000	56,686,000	54,208,000
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs	13,382,000	9,092,000	8,034,000
Mortgage loans held-for-sale	554,256,000	388,038,000	497,283,000
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	111,640,000	108,595,000	269,790,000
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	56,579,000	56,686,000	54,208,000
Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	67,837,000
Other real estate owned	51,046,000
Level 3 | Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
MSRs	13,382,000	9,092,000	8,034,000
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	3.00%
Fair Value Inputs, Prepayment Rate	2.00%
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	6.00%
Fair Value Inputs, Prepayment Rate	47.00%
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	5.20%
Fair Value Inputs, Prepayment Rate	11.67%
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	$ 69,812,000	68,613,000	58,572,000
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	$ 25,187,000	25,199,000	24,996,000
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	2.16%
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	2.81%
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	2.48%
Level 3 | Fair Value, Measurements, Nonrecurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Impaired loans—collateral based	$ 67,837,000
Other real estate owned	$ 51,046,000
Level 3 | Fair Value, Measurements, Nonrecurring | 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 | Weighted Average | 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