Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019	Sep. 30, 2019
Derivative [Line Items]
Derivative assets	$ 321,488	$ 103,644	$ 138,286
Derivative liabilities	326,990	129,204	171,009
Interest Rate Contract
Derivative [Line Items]
Derivative assets	253,238	100,569	134,386
Derivative liabilities	318,853	126,805	168,897
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	0	310	256
Derivative liabilities	65,323	25,908	34,734
Designated as Hedging Instrument | Interest Rate Contract | Cash Flow Hedging
Derivative [Line Items]
Derivative assets	0	0	0
Derivative liabilities	49,110	19,385	25,895
Designated as Hedging Instrument | Interest Rate Contract | Fair Value Hedging
Derivative [Line Items]
Derivative assets	0	310	256
Derivative liabilities	16,213	6,523	8,839
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	321,488	103,334	138,030
Derivative liabilities	261,667	103,296	136,275
Not Designated as Hedging Instrument | Interest Rate Contract
Derivative [Line Items]
Derivative assets	253,238	100,259	134,130
Derivative liabilities	253,530	100,897	134,163
Not Designated as Hedging Instrument | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative assets	68,201	2,860	3,373
Derivative liabilities	0	259	148
Not Designated as Hedging Instrument | Forward Commitments to Sell Mortgage Loans
Derivative [Line Items]
Derivative assets	0	142	176
Derivative liabilities	8,088	2,070	1,658
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative assets	49	73	351
Derivative liabilities	$ 49	$ 70	$ 306