Shareholders' Equity And Earnings Per Share (Components Of Other Comprehensive Income (Loss)) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning			$ 2,695,617	$ 2,352,274
Other comprehensive income (loss) during the period, net of tax, before reclassifications	$ 5,087	$ 925	24,124	25,516
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	(16)	(1,359)	618	(2,094)
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	(20)	2,295	(900)	6,707
Total other comprehensive income	5,051	1,861	23,842	30,129
Balance at the end	2,908,925	2,674,474	2,908,925	2,674,474
Accumulated Unrealized Gains (Losses) on Securities
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	(15,022)	3,971	(29,309)	(17,674)
Other comprehensive income (loss) during the period, net of tax, before reclassifications	653	1,532	15,815	20,444
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	(24)	(2,005)	(19)	(3,684)
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	(20)	2,295	(900)	6,707
Total other comprehensive income	609	1,822	14,896	23,467
Balance at the end	(14,413)	5,793	(14,413)	5,793
Accumulated Unrealized Losses on Derivative Instruments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	4,959	(2,220)	4,165	(2,193)
Other comprehensive income (loss) during the period, net of tax, before reclassifications	228	1,037	393	66
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	8	646	637	1,590
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	0	0	0	0
Total other comprehensive income	236	1,683	1,030	1,656
Balance at the end	5,195	(537)	5,195	(537)
Accumulated Foreign Currency Translation Adjustments
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	(36,474)	(36,191)	(40,184)	(42,841)
Other comprehensive income (loss) during the period, net of tax, before reclassifications	4,206	(1,644)	7,916	5,006
Amount reclassified from accumulated other comprehensive income (loss) into net income, net of tax	0	0	0	0
Amount reclassified from accumulated other comprehensive income related to amortization of unrealized losses on investment securities transferred to held-to-maturity from available-for-sale, net of tax	0	0	0	0
Total other comprehensive income	4,206	(1,644)	7,916	5,006
Balance at the end	(32,268)	(37,835)	(32,268)	(37,835)
Accumulated other comprehensive loss
Activity Accumulated Other Comprehensive Income [Roll Forward]
Balance at the beginning	(46,537)	(34,440)	(65,328)	(62,708)
Total other comprehensive income			23,842	30,129
Balance at the end	$ (41,486)	$ (32,579)	$ (41,486)	$ (32,579)