Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	$ 199,578	$ 180,428	$ 194,320	$ 174,990
Provision (benefit) charged to expense	10,150	14,250	27,900	43,850
Charge-offs	(10,654)	(9,424)	(26,910)	(38,108)
Recoveries	2,729	2,671	6,493	7,193
Balance, end of period	199,578	180,428	194,320	174,990	$ 201,803	$ 194,320	$ 187,925
ALLL, Individually evaluated for impairment					17,786		19,503
ALLL, Collectively evaluated for impairment					184,017		168,422
Loan and lease balances, Individually evaluated for impairment					270,156		257,711
Loan and lease balances, Collectively evaluated for impairment					17,176,265		16,365,690
Loans and leases					17,446,421	17,026,588	16,623,401
Residential Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	18,427	24,413	23,226	25,876
Provision (benefit) charged to expense	(348)	1,076	(4,436)	991
Charge-offs	(585)	(1,304)	(1,940)	(3,536)
Recoveries	280	554	924	1,408
Balance, end of period	18,427	24,413	23,226	25,876	17,774	23,226	24,739
ALLL, Individually evaluated for impairment					4,925		9,443
ALLL, Collectively evaluated for impairment					12,849		15,296
Loan and lease balances, Individually evaluated for impairment					116,706		122,020
Loan and lease balances, Collectively evaluated for impairment					4,382,735		4,112,027
Loans and leases					4,499,441	4,254,682	4,234,047
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	42,488	42,956	45,233	42,052
Provision (benefit) charged to expense	(41)	4,985	6,847	12,458
Charge-offs	(6,197)	(5,259)	(18,273)	(14,236)
Recoveries	1,894	1,313	4,337	3,721
Balance, end of period	42,488	42,956	45,233	42,052	38,144	45,233	43,995
ALLL, Individually evaluated for impairment					1,689		3,005
ALLL, Collectively evaluated for impairment					36,455		40,990
Loan and lease balances, Individually evaluated for impairment					46,224		46,208
Loan and lease balances, Collectively evaluated for impairment					2,520,759		2,661,135
Loans and leases					2,566,983	2,684,500	2,707,343
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	79,964	73,822	71,905	66,686
Provision (benefit) charged to expense	12,166	4,351	21,905	25,447
Charge-offs	(3,002)	(2,561)	(5,321)	(17,294)
Recoveries	466	370	1,105	1,143
Balance, end of period	79,964	73,822	71,905	66,686	89,594	71,905	75,982
ALLL, Individually evaluated for impairment					10,844		6,579
ALLL, Collectively evaluated for impairment					78,750		69,403
Loan and lease balances, Individually evaluated for impairment					85,385		58,197
Loan and lease balances, Collectively evaluated for impairment					5,262,918		4,721,605
Loans and leases					5,348,303	4,940,931	4,779,802
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	52,402	33,622	47,477	34,889
Provision (benefit) charged to expense	(2,129)	2,953	2,987	3,921
Charge-offs	(749)	0	(951)	(2,521)
Recoveries	10	194	21	480
Balance, end of period	52,402	33,622	47,477	34,889	49,534	47,477	36,769
ALLL, Individually evaluated for impairment					290		467
ALLL, Collectively evaluated for impairment					49,244		36,302
Loan and lease balances, Individually evaluated for impairment					18,199		24,423
Loan and lease balances, Collectively evaluated for impairment					4,446,718		4,256,090
Loans and leases					4,464,917	4,510,846	4,280,513
Finance Leases Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Balance, beginning of period	6,297	5,615	6,479	5,487
Provision (benefit) charged to expense	502	885	597	1,033
Charge-offs	(121)	(300)	(425)	(521)
Recoveries	79	240	106	441
Balance, end of period	$ 6,297	$ 5,615	$ 6,479	$ 5,487	6,757	6,479	6,440
ALLL, Individually evaluated for impairment					38		9
ALLL, Collectively evaluated for impairment					6,719		6,431
Loan and lease balances, Individually evaluated for impairment					3,642		6,863
Loan and lease balances, Collectively evaluated for impairment					563,135		614,833
Loans and leases					$ 566,777	$ 635,629	$ 621,696