Fair Value Measurement (Schedule Of Reconciliation Of Assets And Liabilities Measured At Fair Value Using Significant Unobservable Inputs (Level 3) On A Recurring Basis) (Details) - Level 3 - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Junior Subordinated Debentures
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Junior subordinated debentures, beginning balance	$ 265,423	$ 258,660	$ 262,209	$ 255,457
Junior subordinated debentures, change included in earnings	5,043	4,486	14,595	13,160
Junior subordinated debentures, purchases and issuances	0	0	0	0
Junior subordinated debentures, sales and settlements	(3,591)	(3,032)	(9,929)	(8,503)
Junior subordinated debentures, ending balance	266,875	260,114	266,875	260,114
Junior subordinated debentures, net change in unrealized gains or (losses) relating to items held at end of period	5,043	4,486	14,595	13,160
Interest Rate Lock Commitments
Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobservable Inputs	4,781	10,577	4,781	10,577	$ 4,746	$ 4,076	$ 11,028	$ 3,631
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Gain (Loss) Included in Earnings	884	1,585	2,261	5,306
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobserved Inputs, Purchase And Issuance	10,028	19,503	31,992	50,785
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis with Unobserved Inputs Sales And Settlements	(10,877)	(21,539)	(33,548)	(49,145)
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Inputs Reconciliation, Period Increase (Decrease)	4,781	10,577	4,781	10,577
Mortgage Servicing Rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Mortgage servicing rights, beginning balance	141,832	112,095	142,973	131,817
Mortgage servicing rights, change included in earnings	(9,233)	(7,826)	(25,234)	(42,391)
Mortgage servicing rights, purchases and issuances	8,626	10,177	23,486	25,020
Mortgage servicing rights, sales and settlements	0	0	0	0
Mortgage servicing rights, ending balance	141,225	114,446	141,225	114,446
Mortgage servicing rights, net change in unrealized gains or (losses) relating to items held at end of period	$ (4,730)	$ (3,424)	$ (12,954)	$ (35,386)