Allowance for Loan and Lease Loss and Credit Quality (Activity In The Allowance For Loan And Lease Losses) (Details) - 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
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	$ 136,867	$ 131,042	$ 133,984	$ 130,322
Charge-offs	(13,222)	(13,088)	(40,168)	(33,620)
Recoveries	3,861	2,647	11,361	8,487
(Recapture) provision	11,997	13,091	34,326	28,503
Balance, end of period, allowance	139,503	133,692	139,503	133,692
Allowance for loans and leases:
Collectively evaluated for impairment					$ 135,029		$ 127,346
Individually evaluated for impairment					1,165		2,426
Total	136,867	131,042	133,984	130,322	139,503	$ 133,984	133,692
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					18,398,201		17,028,264
Individually evaluated for impairment					72,957		62,473
Total					18,677,762	17,508,663	17,392,051
Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					3,309		3,920
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					206,604	280,400	301,314
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	47,414	50,584	47,795	54,293
Charge-offs	(503)	(1,071)	(1,651)	(2,137)
Recoveries	676	628	2,533	1,348
(Recapture) provision	(696)	(2,839)	(1,786)	(6,202)
Balance, end of period, allowance	46,891	47,302	46,891	47,302
Allowance for loans and leases:
Collectively evaluated for impairment					43,792		43,473
Individually evaluated for impairment					749		1,099
Total	47,414	50,584	47,795	54,293	46,891	47,795	47,302
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					9,440,129		9,051,925
Individually evaluated for impairment					40,832		39,737
Total					9,644,507		9,339,002
Commercial real estate | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					2,350		2,730
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					163,546		247,340
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	60,057	52,355	58,840	47,487
Charge-offs	(10,504)	(8,975)	(31,304)	(23,224)
Recoveries	2,121	1,186	5,662	3,633
(Recapture) provision	9,900	12,846	28,376	29,516
Balance, end of period, allowance	61,574	57,412	61,574	57,412
Allowance for loans and leases:
Collectively evaluated for impairment					60,809		55,735
Individually evaluated for impairment					416		1,327
Total	60,057	52,355	58,840	47,487	61,574	58,840	57,412
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					4,054,600		3,521,571
Individually evaluated for impairment					32,125		22,736
Total					4,091,441		3,550,976
Commercial | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					349		350
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					4,716		6,669
Residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	18,051	20,146	17,946	22,017
Charge-offs	(128)	(915)	(745)	(1,546)
Recoveries	287	137	597	661
(Recapture) provision	755	626	1,167	(1,138)
Balance, end of period, allowance	18,965	19,994	18,965	19,994
Allowance for loans and leases:
Collectively evaluated for impairment					18,383		19,225
Individually evaluated for impairment					0		0
Total	18,051	20,146	17,946	22,017	18,965	17,946	19,994
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					4,136,418		3,830,060
Individually evaluated for impairment					0		0
Total					4,174,292		3,876,556
Residential | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					582		769
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					37,874		46,496
Consumer & other, net
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	11,345	7,957	9,403	6,525
Charge-offs	(2,087)	(2,127)	(6,468)	(6,713)
Recoveries	777	696	2,569	2,845
(Recapture) provision	2,038	2,458	6,569	6,327
Balance, end of period, allowance	12,073	8,984	12,073	8,984
Allowance for loans and leases:
Collectively evaluated for impairment					12,045		8,913
Individually evaluated for impairment					0		0
Total	$ 11,345	$ 7,957	$ 9,403	$ 6,525	12,073	$ 9,403	8,984
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					767,054		624,708
Individually evaluated for impairment					0		0
Total					767,522		625,517
Consumer & other, net | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					28		71
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					$ 468		$ 809