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, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Rollforward of AOCI from Cash Flow Hedging Derivatives [Roll Forward]
Unrealized gain at beginning of period	$ 5,746	$ 14,977	$ 10,742	$ 11,902
Amount reclassified from accumulated other comprehensive income to interest expense on deposits and other borrowings	(4,081)	(1,339)	(7,643)	(2,019)
Amount of (loss) gain recognized in other comprehensive income	(18,087)	2,421	(19,521)	6,176
Unrealized (loss) gain at end of period	$ (16,422)	$ 16,059	$ (16,422)	$ 16,059