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		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Dec. 31, 2018	Jun. 30, 2018
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	$ 144,872	$ 141,933	$ 144,871	$ 140,608
Charge-offs	(16,707)	(14,815)	(33,859)	(30,627)
Recoveries	3,552	4,119	7,021	7,600
Provision	19,352	13,319	33,036	26,975
Balance, end of period, allowance	151,069	144,556	151,069	144,556
Allowance for loans and leases:
Collectively evaluated for impairment					$ 148,881		$ 141,138
Individually evaluated for impairment					170		821
Total	144,872	141,933	144,871	140,608	151,069	$ 144,871	144,556
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					20,812,476		19,435,607
Individually evaluated for impairment					27,343		46,011
Total					20,953,371	20,422,666	19,639,494
Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					2,018		2,597
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					113,552	134,500	157,876
Commercial real estate
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	47,841	46,005	47,904	45,765
Charge-offs	(387)	(362)	(2,538)	(673)
Recoveries	219	289	556	506
Provision	1,324	1,353	3,075	1,687
Balance, end of period, allowance	48,997	47,285	48,997	47,285
Allowance for loans and leases:
Collectively evaluated for impairment					47,337		44,668
Individually evaluated for impairment					167		814
Total	47,841	46,005	47,904	45,765	48,997	47,904	47,285
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					10,099,981		9,776,975
Individually evaluated for impairment					18,707		28,786
Total					10,207,658		9,930,315
Commercial real estate | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					1,493		1,803
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					88,970		124,554
Commercial
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	64,370	64,626	63,957	63,305
Charge-offs	(14,697)	(12,869)	(27,907)	(26,344)
Recoveries	2,611	3,171	4,965	5,624
Provision	16,069	10,837	27,338	23,180
Balance, end of period, allowance	68,353	65,765	68,353	65,765
Allowance for loans and leases:
Collectively evaluated for impairment					68,156		65,378
Individually evaluated for impairment					3		7
Total	64,370	64,626	68,353	65,765	68,353	63,957	65,765
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					4,992,265		4,504,361
Individually evaluated for impairment					8,636		17,225
Total					5,001,512		4,525,354
Commercial | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					194		380
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					611		3,768
Residential
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	22,173	19,833	22,034	19,360
Charge-offs	(67)	(460)	(202)	(706)
Recoveries	150	98	305	301
Provision	1,398	804	1,517	1,320
Balance, end of period, allowance	23,654	20,275	23,654	20,275
Allowance for loans and leases:
Collectively evaluated for impairment					23,331		19,902
Individually evaluated for impairment					0		0
Total	22,173	19,833	22,034	19,360	23,654	22,034	20,275
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					5,187,194		4,508,961
Individually evaluated for impairment					0		0
Total					5,210,858		4,538,104
Residential | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					323		373
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					23,664		29,143
Consumer & other, net
Allowance for Loan and Lease Losses [Roll Forward]
Balance, beginning of period, allowance	10,488	11,469	10,976	12,178
Charge-offs	(1,556)	(1,124)	(3,212)	(2,904)
Recoveries	572	561	1,195	1,169
Provision	561	325	1,106	788
Balance, end of period, allowance	10,065	11,231	10,065	11,231
Allowance for loans and leases:
Collectively evaluated for impairment					10,057		11,190
Individually evaluated for impairment					0		0
Total	$ 10,488	$ 11,469	$ 10,065	$ 11,231	10,065	$ 10,976	11,231
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Collectively evaluated for impairment					533,036		645,310
Individually evaluated for impairment					0		0
Total					533,343		645,721
Consumer & other, net | Receivables Acquired with Deteriorated Credit Quality
Allowance for loans and leases:
Loans acquired with deteriorated credit quality					8		41
Financing Receivable, Allowance for Credit Loss, Loans And Leases [Abstract]
Loans acquired with deteriorated credit quality					$ 307		$ 411