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	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016
Junior Subordinated Debentures
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Junior subordinated debentures, at fair value, beginning balance	$ 262,209	$ 255,457
Junior subordinated debentures, at fair value, change included in earnings	28,147	17,815
Fair value, measurement with unobservable inputs reconciliation, recurring basis, liability, purchases and issuances	0	0
Junior subordinated debentures, at fair value, sales and settlements	(13,201)	(11,063)
Junior subordinated debentures, at fair value, ending balance	277,155	262,209
Junior subordinated debentures, at fair value, net change in unrealized gains or (losses) relating to items held at end of period	28,147	17,815
Interest Rate Lock Commitments
Fair Value, Net Derivative Asset (Liability) Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Interest rate lock commitment, beginning balance	4,076	3,631
Interest rate lock commitment, change included in earnings	2,461	834
Fair value, measurement with unobservable inputs reconciliation, recurring basis, asset and liability, purchases and issuances	39,310	58,881
Interest rate lock commitment, sales and settlements	(41,095)	(59,270)
Interest rate lock commitment, ending balance	4,752	4,076
Interest rate lock commitment, net change in unrealized gains or (losses) relating to items held at end of period	4,752	4,076
Mortgage Servicing Rights
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Mortgage servicing rights, at fair value, beginning balance	142,973	131,817
Mortgage servicing rights, at fair value, change included in earnings	(23,267)	(25,926)
Fair value measurement with unobservable inputs reconciliation recurring basis asset purchases and issuances	33,445	37,082
Mortgage servicing rights, at fair value, sales and settlements	0	0
Mortgage servicing rights, at fair value, ending balance	153,151	142,973
Mortgage servicing rights, at fair value, net change in unrealized gains or (losses) relating to items held at end of period	$ (6,799)	$ (14,133)