Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Derivative [Line Items]
Derivative assets	$ 96,153	$ 52,069	$ 48,198
Derivative liabilities	71,381	35,671	35,773
Interest Rate Contract
Derivative [Line Items]
Derivative assets	91,262	48,985	45,168
Derivative liabilities	69,342	33,716	34,035
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	21,397	14,846	10,679
Derivative liabilities	0	12	53
Designated as Hedging Instrument | Interest Rate Contract | Cash Flow Hedging
Derivative [Line Items]
Derivative assets	16,271	11,914	8,643
Derivative liabilities	0	12	0
Designated as Hedging Instrument | Interest Rate Contract | Fair Value Hedging
Derivative [Line Items]
Derivative assets	5,126	2,932	2,036
Derivative liabilities	0	0	53
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	74,756	37,223	37,519
Derivative liabilities	71,381	35,659	35,720
Not Designated as Hedging Instrument | Interest Rate Contract
Derivative [Line Items]
Derivative assets	69,865	34,139	34,489
Derivative liabilities	69,342	33,704	33,982
Not Designated as Hedging Instrument | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative assets	4,128	2,843	2,851
Derivative liabilities	0	269	1
Not Designated as Hedging Instrument | Forward Commitments to Sell Mortgage Loans
Derivative [Line Items]
Derivative assets	12	14	19
Derivative liabilities	1,330	1,457	1,495
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative assets	751	227	160
Derivative liabilities	$ 709	$ 229	$ 242