Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
FINANCIAL ASSETS:
Cash and cash equivalents	$ 569,189	$ 634,280	$ 684,646	$ 1,449,432
Equity and other, at fair value	63,295	12,255
Investment securities available for sale	2,947,414	3,065,769
Investment securities held to maturity	3,667	3,803
Loans held for sale	299,739	259,518
Loans and leases, net (1)	19,172,656	18,939,576
Restricted equity securities	43,501	43,508
Residential mortgage servicing rights	164,760	153,151	$ 142,344	$ 142,973
Bank owned life insurance assets	307,745	306,864
Derivatives	19,145	32,256
FINANCIAL LIABILITIES:
Deposits	20,106,856	19,948,300
Securities sold under agreements to repurchase	291,984	294,299
Term debt	801,868	802,357
Junior subordinated debentures, at fair value	278,410	277,155
Junior subordinated debentures, at amortized cost	88,895	100,609
Derivatives	22,675	9,288
Carrying Value
FINANCIAL ASSETS:
Cash and cash equivalents	569,189	634,280
Equity and other, at fair value	63,295	12,255
Investment securities available for sale	2,947,414	3,065,769
Investment securities held to maturity	3,667	3,803
Loans held for sale	299,739	259,518
Loans and leases, net (1)	19,172,656	18,939,576
Restricted equity securities	43,501	43,508
Residential mortgage servicing rights	164,760	153,151
Bank owned life insurance assets	307,745	306,864
Derivatives	19,145	32,256
Visa Class B common stock	0	0
FINANCIAL LIABILITIES:
Deposits	20,106,856	19,948,300
Securities sold under agreements to repurchase	291,984	294,299
Term debt	801,868	802,357
Junior subordinated debentures, at fair value	278,410	277,155
Junior subordinated debentures, at amortized cost	88,895	100,609
Derivatives	22,675	9,288
Estimated Fair Value
FINANCIAL ASSETS:
Cash and cash equivalents	569,189	634,280
Equity and other, at fair value	63,295	12,255
Investment securities available for sale	2,947,414	3,065,769
Investment securities held to maturity	4,669	4,906
Loans held for sale	299,739	259,518
Loans and leases, net (1)	19,047,732	18,936,038
Restricted equity securities	43,501	43,508
Residential mortgage servicing rights	164,760	153,151
Bank owned life insurance assets	307,745	306,864
Derivatives	19,145	32,256
Visa Class B common stock	90,622	86,380
FINANCIAL LIABILITIES:
Deposits	20,079,490	19,930,568
Securities sold under agreements to repurchase	291,984	294,299
Term debt	783,741	790,532
Junior subordinated debentures, at fair value	278,410	277,155
Junior subordinated debentures, at amortized cost	72,044	81,944
Derivatives	$ 22,675	$ 9,288