Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
FINANCIAL ASSETS:
Cash and cash equivalents	$ 330,856	$ 331,994
Trading securities	12,255	10,964
Investment securities available for sale	3,065,769	2,701,220
Investment securities held to maturity	3,803	4,216
Loans held for sale, at fair value	259,518	387,318
Loans and leases, net	19,080,184	17,508,663	$ 16,866,536
Restricted equity securities	43,508	45,528
Residential mortgage servicing rights	153,151	142,973	131,817	$ 117,259
Bank owned life insurance	306,864	299,673
Derivatives	32,256	47,501
FINANCIAL LIABILITIES:
Deposits	19,948,300	19,020,985	$ 17,707,189
Securities sold under agreements to repurchase	294,299	352,948
Term debt	802,357	852,397
Junior subordinated debentures, at amortized cost	100,609	100,931
Carrying Value
FINANCIAL ASSETS:
Cash and cash equivalents	634,280	1,449,432
Trading securities	12,255	10,964
Investment securities available for sale	3,065,769	2,701,220
Investment securities held to maturity	3,803	4,216
Loans held for sale, at fair value	259,518	387,318
Loans and leases, net	18,939,576	17,374,679
Restricted equity securities	43,508	45,528
Residential mortgage servicing rights	153,151	142,973
Bank owned life insurance	306,864	299,673
Derivatives	32,256	47,501
Visa Class B common stock	0	0
FINANCIAL LIABILITIES:
Deposits	19,948,300	19,020,985
Securities sold under agreements to repurchase	294,299	352,948
Term debt	802,357	852,397
Junior subordinated debentures, at fair value	277,155	262,209
Junior subordinated debentures, at amortized cost	100,609	100,931
Derivatives	9,288	37,063
Estimated Fair Value
FINANCIAL ASSETS:
Cash and cash equivalents	634,280	1,449,432
Trading securities	12,255	10,964
Investment securities available for sale	3,065,769	2,701,220
Investment securities held to maturity	4,906	5,217
Loans held for sale, at fair value	259,518	387,318
Loans and leases, net	18,936,038	17,385,156
Restricted equity securities	43,508	45,528
Residential mortgage servicing rights	153,151	142,973
Bank owned life insurance	306,864	299,673
Derivatives	32,256	47,501
Visa Class B common stock	86,380	59,107
FINANCIAL LIABILITIES:
Deposits	19,930,568	19,016,330
Securities sold under agreements to repurchase	294,299	352,948
Term debt	790,532	844,377
Junior subordinated debentures, at fair value	277,155	262,209
Junior subordinated debentures, at amortized cost	81,944	77,640
Derivatives	$ 9,288	$ 37,063