Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
FINANCIAL ASSETS:
Cash and cash equivalents	$ 262,655	$ 331,994
Trading securities	11,241	10,964
Investment securities available for sale	3,243,408	2,701,220
Investment securities held to maturity	4,121	4,216
Loans held for sale	372,073	387,318
Loans and leases	17,829,638	17,508,663	$ 16,955,583
Restricted equity securities	45,522	45,528
Residential mortgage servicing rights	142,344	142,973	$ 117,172	$ 131,817
Bank owned life insurance assets	301,777	299,673
Derivatives	34,029	47,501
FINANCIAL LIABILITIES:
Deposits	19,167,293	19,020,985
Securities sold under agreements to repurchase	304,280	352,948
Term debt	852,308	852,397
Junior subordinated debentures, at fair value	263,605	262,209
Junior subordinated debentures, at amortized cost	100,851	100,931
Derivatives	10,438	37,063
Carrying Value
FINANCIAL ASSETS:
Cash and cash equivalents	684,646	1,449,432
Trading securities	11,241	10,964
Investment securities available for sale	3,243,408	2,701,220
Investment securities held to maturity	4,121	4,216
Loans held for sale	372,073	387,318
Loans and leases	17,693,346	17,374,679
Restricted equity securities	45,522	45,528
Residential mortgage servicing rights	142,344	142,973
Bank owned life insurance assets	301,777	299,673
Derivatives	34,029	47,501
Visa Class B common stock	0	0
FINANCIAL LIABILITIES:
Deposits	19,167,293	19,020,985
Securities sold under agreements to repurchase	304,280	352,948
Term debt	852,308	852,397
Junior subordinated debentures, at fair value	263,605	262,209
Junior subordinated debentures, at amortized cost	100,851	100,931
Derivatives	10,438	37,063
Estimated Fair Value
FINANCIAL ASSETS:
Cash and cash equivalents	684,646	1,449,432
Trading securities	11,241	10,964
Investment securities available for sale	3,243,408	2,701,220
Investment securities held to maturity	5,146	5,217
Loans held for sale	372,073	387,318
Loans and leases	17,710,155	17,385,156
Restricted equity securities	45,522	45,528
Residential mortgage servicing rights	142,344	142,973
Bank owned life insurance assets	301,777	299,673
Derivatives	34,029	47,501
Visa Class B common stock	67,327	59,107
FINANCIAL LIABILITIES:
Deposits	19,162,214	19,016,330
Securities sold under agreements to repurchase	304,280	352,948
Term debt	845,932	844,377
Junior subordinated debentures, at fair value	263,605	262,209
Junior subordinated debentures, at amortized cost	78,051	77,640
Derivatives	$ 10,438	$ 37,063