Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Dec. 31, 2013
FINANCIAL ASSETS:
Cash and cash equivalents	$ 283,773		$ 282,455
Trading securities	9,509		9,999
Investment securities available for sale	2,482,478		2,298,555
Investment securities held to maturity	4,699		5,211
Loans held for sale	398,015		286,802
Loans and leases, net	16,387,934		15,327,732	$ 15,259,201
Restricted equity securities	46,904		119,334
Residential mortgage servicing rights	124,814	$ 127,206	117,259	118,725	$ 114,192	$ 47,765
Bank owned life insurance assets	297,321		294,296
FDIC indemnification asset	892	$ 432	4,417	$ 7,811	$ 11,293	$ 23,174
Derivatives	50,608		29,775
FINANCIAL LIABILITIES:
Deposits	17,467,024		16,892,099
Securities sold under agreements to repurchase	323,722		313,321
Term debt	889,358		1,006,395
Junior subordinated debentures, at fair value	253,665		249,294
Junior subordinated debentures, at amortized cost	101,334		101,576
Derivatives	52,796		30,888
Carrying Value [Member]
FINANCIAL ASSETS:
Cash and cash equivalents	957,616		1,605,171
Trading securities	9,509		9,999
Investment securities available for sale	2,482,478		2,298,555
Investment securities held to maturity	4,699		5,211
Loans held for sale	398,015		286,802
Loans and leases, net	16,257,801		15,211,565
Restricted equity securities	46,904		119,334
Residential mortgage servicing rights	124,814		117,259
Bank owned life insurance assets	297,321		294,296
FDIC indemnification asset	892		4,417
Derivatives	50,608		29,775
Visa Class B common stock	0		0
FINANCIAL LIABILITIES:
Deposits	17,467,024		16,892,099
Securities sold under agreements to repurchase	323,722		313,321
Term debt	889,358		1,006,395
Junior subordinated debentures, at fair value	253,665		249,294
Junior subordinated debentures, at amortized cost	101,334		101,576
Derivatives	52,796		30,888
Estimated Fair Value [Member]
FINANCIAL ASSETS:
Cash and cash equivalents	957,616		1,605,171
Trading securities	9,509		9,999
Investment securities available for sale	2,482,478		2,298,555
Investment securities held to maturity	5,280		5,554
Loans held for sale	398,015		286,802
Loans and leases, net	16,279,789		15,252,083
Restricted equity securities	46,904		119,334
Residential mortgage servicing rights	124,814		117,259
Bank owned life insurance assets	297,321		294,296
FDIC indemnification asset	254		2,058
Derivatives	50,608		29,775
Visa Class B common stock	52,576		49,663
FINANCIAL LIABILITIES:
Deposits	17,474,312		16,893,890
Securities sold under agreements to repurchase	323,722		313,321
Term debt	905,454		1,018,948
Junior subordinated debentures, at fair value	253,665		249,294
Junior subordinated debentures, at amortized cost	75,127		73,840
Derivatives	$ 52,796		$ 30,888