Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Dec. 31, 2015
FINANCIAL ASSETS:
Cash and cash equivalents	$ 845,566		$ 1,449,432	$ 1,466,441		$ 773,725
Trading securities	11,919		10,964
Investment securities available for sale	3,047,358		2,701,220
Investment securities held to maturity	3,905		4,216
Loans held for sale	417,470		387,318
Loans and leases, net	18,538,259		17,374,679
Restricted equity securities	45,509		45,528
Residential mortgage servicing rights	141,225	$ 141,832	142,973	$ 114,446	$ 112,095	$ 131,817
Bank owned life insurance assets	305,572		299,673
Derivatives	41,735		47,501
FINANCIAL LIABILITIES:
Deposits	19,851,910		19,020,985
Securities sold under agreements to repurchase	321,542		352,948
Term debt	852,306		852,397
Junior subordinated debentures, at fair value	266,875		262,209
Junior subordinated debentures, at amortized cost	100,690		100,931
Derivatives	5,811		37,063
Carrying Value
FINANCIAL ASSETS:
Cash and cash equivalents	845,566		1,449,432
Trading securities	11,919		10,964
Investment securities available for sale	3,047,358		2,701,220
Investment securities held to maturity	3,905		4,216
Loans held for sale	417,470		387,318
Loans and leases, net	18,538,259		17,374,679
Restricted equity securities	45,509		45,528
Residential mortgage servicing rights	141,225		142,973
Bank owned life insurance assets	305,572		299,673
Derivatives	41,735		47,501
Visa Class B common stock	0		0
FINANCIAL LIABILITIES:
Deposits	19,851,910		19,020,985
Securities sold under agreements to repurchase	321,542		352,948
Term debt	852,306		852,397
Junior subordinated debentures, at fair value	266,875		262,209
Junior subordinated debentures, at amortized cost	100,690		100,931
Derivatives	5,811		37,063
Estimated Fair Value
FINANCIAL ASSETS:
Cash and cash equivalents	845,566		1,449,432
Trading securities	11,919		10,964
Investment securities available for sale	3,047,358		2,701,220
Investment securities held to maturity	5,019		5,217
Loans held for sale	417,470		387,318
Loans and leases, net	18,492,760		17,385,156
Restricted equity securities	45,509		45,528
Residential mortgage servicing rights	141,225		142,973
Bank owned life insurance assets	305,572		299,673
Derivatives	41,735		47,501
Visa Class B common stock	79,728		59,107
FINANCIAL LIABILITIES:
Deposits	19,846,636		19,016,330
Securities sold under agreements to repurchase	321,542		352,948
Term debt	846,390		844,377
Junior subordinated debentures, at fair value	266,875		262,209
Junior subordinated debentures, at amortized cost	79,013		77,640
Derivatives	$ 5,811		$ 37,063