Fair Value Measurement (Schedule Of Carrying Value And Fair Value Of Financial Instruments Not Recorded At Fair Value) (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015
FINANCIAL ASSETS:
Cash and cash equivalents	$ 615,964		$ 1,449,432	$ 905,363		$ 773,725
Trading securities	11,467		10,964
Investment securities available for sale	3,132,566		2,701,220
Investment securities held to maturity	4,017		4,216
Loans held for sale	451,350		387,318
Loans and leases, net	18,184,275		17,374,679
Restricted equity securities	45,511		45,528
Residential mortgage servicing rights	141,832	$ 142,344	142,973	$ 112,095	$ 117,172	$ 131,817
Bank owned life insurance assets	303,894		299,673
Derivatives	42,028		47,501
FINANCIAL LIABILITIES:
Deposits	19,459,950		19,020,985
Securities sold under agreements to repurchase	330,189		352,948
Term debt	852,219		852,397
Junior subordinated debentures, at fair value	265,423		262,209
Junior subordinated debentures, at amortized cost	100,770		100,931
Derivatives	5,660		37,063
Carrying Value
FINANCIAL ASSETS:
Cash and cash equivalents	615,964		1,449,432
Trading securities	11,467		10,964
Investment securities available for sale	3,132,566		2,701,220
Investment securities held to maturity	4,017		4,216
Loans held for sale	451,350		387,318
Loans and leases, net	18,184,275		17,374,679
Restricted equity securities	45,511		45,528
Residential mortgage servicing rights	141,832		142,973
Bank owned life insurance assets	303,894		299,673
Derivatives	42,028		47,501
Visa Class B common stock	0		0
FINANCIAL LIABILITIES:
Deposits	19,459,950		19,020,985
Securities sold under agreements to repurchase	330,189		352,948
Term debt	852,219		852,397
Junior subordinated debentures, at fair value	265,423		262,209
Junior subordinated debentures, at amortized cost	100,770		100,931
Derivatives	5,660		37,063
Estimated Fair Value
FINANCIAL ASSETS:
Cash and cash equivalents	615,964		1,449,432
Trading securities	11,467		10,964
Investment securities available for sale	3,132,566		2,701,220
Investment securities held to maturity	5,071		5,217
Loans held for sale	451,350		387,318
Loans and leases, net	18,166,230		17,385,156
Restricted equity securities	45,511		45,528
Residential mortgage servicing rights	141,832		142,973
Bank owned life insurance assets	303,894		299,673
Derivatives	42,028		47,501
Visa Class B common stock	71,046		59,107
FINANCIAL LIABILITIES:
Deposits	19,456,321		19,016,330
Securities sold under agreements to repurchase	330,189		352,948
Term debt	847,076		844,377
Junior subordinated debentures, at fair value	265,423		262,209
Junior subordinated debentures, at amortized cost	78,586		77,640
Derivatives	$ 5,660		$ 37,063