Derivative Financial Instruments (Rollforward Of Amounts In Accumulated Other Comprehensive Income Related To Interest Rate Swaps Designated As Cash Flow Hedges) (Detail) - Interest Rate Contract - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Unrealized gain at beginning of period	$ 14,977	$ 8,559	$ 11,902	$ 6,944
Amount reclassified from accumulated other comprehensive loss to interest expense on deposits and junior subordinated debentures	(1,339)	681	(2,019)	1,037
Amount of gain (loss) recognized in other comprehensive income	2,421	(991)	6,176	268
Unrealized gain at end of period	$ 16,059	$ 8,249	$ 16,059	$ 8,249