Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014
FINANCIAL ASSETS:
Cash and cash equivalents	$ 369,535		$ 277,645
Trading securities	10,188		9,586
Investment securities available for sale	2,482,072		2,522,539
Investment securities held to maturity	4,382		4,609
Loans held for sale	552,681		363,275
Loans and leases	17,355,240		16,866,536	$ 15,988,752
Restricted equity securities	47,542		46,949
Residential mortgage servicing rights	112,095	$ 117,172	131,817	$ 127,206	$ 116,365	$ 117,259
Bank owned life insurance assets	295,444		291,892
Derivatives	93,747		43,549
FINANCIAL LIABILITIES:
Deposits	18,258,474		17,707,189
Securities sold under agreements to repurchase	360,234		304,560
Term debt	902,999		888,769
Junior subordinated debentures, at fair value	258,660		255,457
Junior subordinated debentures, at amortized cost	101,093		101,254
Derivatives	95,103		41,514
Carrying Value
FINANCIAL ASSETS:
Cash and cash equivalents	905,363		773,725
Trading securities	10,188		9,586
Investment securities available for sale	2,482,072		2,522,539
Investment securities held to maturity	4,382		4,609
Loans held for sale	552,681		363,275
Loans and leases	17,224,198		16,736,214
Restricted equity securities	47,542		46,949
Residential mortgage servicing rights	112,095		131,817
Bank owned life insurance assets	295,444		291,892
Derivatives	93,747		43,549
Visa Class B common stock	0		0
FINANCIAL LIABILITIES:
Deposits	18,258,474		17,707,189
Securities sold under agreements to repurchase	360,234		304,560
Term debt	902,999		888,769
Junior subordinated debentures, at fair value	258,660		255,457
Junior subordinated debentures, at amortized cost	101,093		101,254
Derivatives	95,103		41,514
Estimated Fair Value
FINANCIAL ASSETS:
Cash and cash equivalents	905,363		773,725
Trading securities	10,188		9,586
Investment securities available for sale	2,482,072		2,522,539
Investment securities held to maturity	5,250		5,590
Loans held for sale	552,762		363,275
Loans and leases	17,386,430		16,661,079
Restricted equity securities	47,542		46,949
Residential mortgage servicing rights	112,095		131,817
Bank owned life insurance assets	295,444		291,892
Derivatives	93,747		43,549
Visa Class B common stock	56,198		58,751
FINANCIAL LIABILITIES:
Deposits	18,271,000		17,709,555
Securities sold under agreements to repurchase	360,234		304,560
Term debt	914,008		890,852
Junior subordinated debentures, at fair value	258,660		255,457
Junior subordinated debentures, at amortized cost	76,597		75,654
Derivatives	$ 95,103		$ 41,514