Derivative Financial Instruments (Rollforward Of Amounts In Accumulated Other Comprehensive Income Related To Interest Rate Swaps Designated As Cash Flow Hedges) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Amount of gain recognized in other comprehensive income	$ 155	$ 236	$ 3,196	$ 1,030
Interest Rate Contract
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Unrealized gain at beginning of period	16,059	8,249	11,902	6,944
Amount reclassified from accumulated other comprehensive loss to interest expense on deposits and junior subordinated debentures	(2,319)	14	(4,338)	1,051
Amount of gain recognized in other comprehensive income	2,531	380	8,707	648
Unrealized gain at end of period	$ 16,271	$ 8,643	$ 16,271	$ 8,643