Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2020	Dec. 31, 2019	Mar. 31, 2019
Derivative [Line Items]
Derivative assets	$ 301,368	$ 103,644	$ 75,504
Derivative liabilities	367,620	129,204	73,868
Interest Rate Contract
Derivative [Line Items]
Derivative assets	259,986	100,569	68,317
Derivative liabilities	329,590	126,805	69,292
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	0	310	4,613
Derivative liabilities	73,397	25,908	5,756
Designated as Hedging Instrument | Interest Rate Contract | Cash Flow Hedging
Derivative [Line Items]
Derivative assets	0	0	3,353
Derivative liabilities	57,274	19,385	2,589
Designated as Hedging Instrument | Interest Rate Contract | Fair Value Hedging
Derivative [Line Items]
Derivative assets	0	310	1,260
Derivative liabilities	16,123	6,523	3,167
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	301,368	103,334	70,891
Derivative liabilities	294,223	103,296	68,112
Not Designated as Hedging Instrument | Interest Rate Contract
Derivative [Line Items]
Derivative assets	259,986	100,259	63,704
Derivative liabilities	256,193	100,897	63,536
Not Designated as Hedging Instrument | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative assets	39,816	2,860	4,387
Derivative liabilities	1,105	259	0
Not Designated as Hedging Instrument | Forward Commitments to Sell Mortgage Loans
Derivative [Line Items]
Derivative assets	1,514	142	2,416
Derivative liabilities	36,872	2,070	4,180
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative assets	52	73	384
Derivative liabilities	$ 53	$ 70	$ 396