Derivative Financial Instruments (Schedule Of Fair Value Of Derivative Financial Instruments) (Detail) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017
Derivative [Line Items]
Derivative assets	$ 78,960	$ 52,069	$ 54,273
Derivative liabilities	55,699	35,671	41,531
Interest Rate Contract
Derivative [Line Items]
Derivative assets	72,970	48,985	48,168
Derivative liabilities	52,443	33,716	35,459
Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	19,974	14,846	11,692
Derivative liabilities	35	12	0
Designated as Hedging Instrument | Interest Rate Contract | Cash Flow Hedging
Derivative [Line Items]
Derivative assets	15,012	11,914	9,311
Derivative liabilities	35	12	0
Designated as Hedging Instrument | Interest Rate Contract | Fair Value Hedging
Derivative [Line Items]
Derivative assets	4,962	2,932	2,381
Derivative liabilities	0	0	0
Not Designated as Hedging Instrument
Derivative [Line Items]
Derivative assets	58,986	37,223	42,581
Derivative liabilities	55,664	35,659	41,531
Not Designated as Hedging Instrument | Interest Rate Contract
Derivative [Line Items]
Derivative assets	52,996	34,139	36,476
Derivative liabilities	52,408	33,704	35,459
Not Designated as Hedging Instrument | Interest Rate Lock Commitments
Derivative [Line Items]
Derivative assets	5,449	2,843	5,600
Derivative liabilities	1,207	269	2,981
Not Designated as Hedging Instrument | Forward Commitments to Sell Mortgage Loans
Derivative [Line Items]
Derivative assets	3	14	69
Derivative liabilities	1,464	1,457	2,656
Not Designated as Hedging Instrument | Foreign Exchange Contract
Derivative [Line Items]
Derivative assets	538	227	436
Derivative liabilities	$ 585	$ 229	$ 435