Fair Value Measurement (Schedule Of Fair Value Assets And Liabilities Measured On Recurring Basis) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	$ 11,919		$ 10,964
Available for sale, at fair value	3,047,358		2,701,220
Loans held for sale, at fair value	417,470		387,318
Residential mortgage servicing rights, at fair value	141,225	$ 141,832	142,973	$ 114,446	$ 112,095	$ 131,817
Derivatives, assets	41,735		47,501
Total assets measured at fair value	3,659,707		3,289,976
Junior subordinated debentures, at fair value	266,875		262,209
Derivatives, liabilities	5,811		37,063
Total liabilities measured at fair value	272,686		299,272
Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	670		670
Derivatives, liabilities	610		874
Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	4,781		4,076
Interest Rate Forward Sales Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	964		8,054
Derivatives, liabilities	807		1,318
Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	35,320		34,701
Derivatives, liabilities	4,394		34,871
Obligations Of States And Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	268		662
Available for sale, at fair value	297,794		307,697
Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	11,651		10,302
U.S. Treasury and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	40,026
Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	2,707,555		2,391,553
Investments In Mutual Funds And Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	1,983		1,970
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, at fair value	0		0
Residential mortgage servicing rights, at fair value	0		0
Total assets measured at fair value	11,651		10,302
Junior subordinated debentures, at fair value	0		0
Total liabilities measured at fair value	0		0
Level 1 | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Derivatives, liabilities	0		0
Level 1 | Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Level 1 | Interest Rate Forward Sales Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Derivatives, liabilities	0		0
Level 1 | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Derivatives, liabilities	0		0
Level 1 | Obligations Of States And Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0		0
Available for sale, at fair value	0		0
Level 1 | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	11,651		10,302
Level 1 | U.S. Treasury and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0
Level 1 | Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0		0
Level 1 | Investments In Mutual Funds And Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0		0
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, at fair value	417,470		387,318
Residential mortgage servicing rights, at fair value	0		0
Total assets measured at fair value	3,502,050		3,132,625
Junior subordinated debentures, at fair value	0		0
Total liabilities measured at fair value	5,811		37,063
Level 2 | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	670		670
Derivatives, liabilities	610		874
Level 2 | Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Level 2 | Interest Rate Forward Sales Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	964		8,054
Derivatives, liabilities	807		1,318
Level 2 | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	35,320		34,701
Derivatives, liabilities	4,394		34,871
Level 2 | Obligations Of States And Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	268		662
Available for sale, at fair value	297,794		307,697
Level 2 | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0		0
Level 2 | U.S. Treasury and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	40,026
Level 2 | Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	2,707,555		2,391,553
Level 2 | Investments In Mutual Funds And Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	1,983		1,970
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held for sale, at fair value	0		0
Residential mortgage servicing rights, at fair value	141,225		142,973
Total assets measured at fair value	146,006		147,049
Junior subordinated debentures, at fair value	266,875		262,209
Total liabilities measured at fair value	266,875		262,209
Level 3 | Foreign Exchange Contract
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Derivatives, liabilities	0		0
Level 3 | Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	4,781		4,076
Level 3 | Interest Rate Forward Sales Commitments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Derivatives, liabilities	0		0
Level 3 | Interest Rate Swap
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivatives, assets	0		0
Derivatives, liabilities	0		0
Level 3 | Obligations Of States And Political Subdivisions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0		0
Available for sale, at fair value	0		0
Level 3 | Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Trading, at fair value	0		0
Level 3 | U.S. Treasury and agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0
Level 3 | Residential Mortgage-Backed Securities And Collateralized Mortgage Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	0		0
Level 3 | Investments In Mutual Funds And Other Equity Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available for sale, at fair value	$ 0		$ 0