Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Derivative [Line Items]
Derivative Assets	$ 191,612	$ 278,423	$ 321,488
Derivative Liabilities	161,314	288,465	326,990
Interest rate contract
Derivative [Line Items]
Derivative Assets	169,315	229,387	253,238
Derivative Liabilities	157,578	275,843	318,853
Designated as hedging instrument
Derivative [Line Items]
Derivative Assets	38,368	8,182	0
Derivative Liabilities	26,481	54,235	65,323
Designated as hedging instrument | Interest rate contract | Interest rate derivatives designated as Cash Flow Hedges
Derivative [Line Items]
Derivative Assets	37,529	8,182	0
Derivative Liabilities	18,054	39,715	49,110
Designated as hedging instrument | Interest rate contract | Interest rate derivatives designated as Fair Value Hedges
Derivative [Line Items]
Derivative Assets	839	0	0
Derivative Liabilities	8,427	14,520	16,213
Not designated as hedging instrument
Derivative [Line Items]
Derivative Assets	153,244	270,241	321,488
Derivative Liabilities	134,833	234,230	261,667
Not designated as hedging instrument | Interest rate contract
Derivative [Line Items]
Derivative Assets	130,947	221,205	253,238
Derivative Liabilities	131,097	221,608	253,530
Not designated as hedging instrument | Interest rate lock commitments
Derivative [Line Items]
Derivative Assets	16,795	48,925	68,201
Derivative Liabilities	753	0	0
Not designated as hedging instrument | Forward commitments to sell mortgage loans
Derivative [Line Items]
Derivative Assets	5,260	0	0
Derivative Liabilities	2,740	12,510	8,088
Not designated as hedging instrument | Foreign exchange contracts
Derivative [Line Items]
Derivative Assets	242	111	49
Derivative Liabilities	$ 243	$ 112	$ 49