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Amount of allowance for credit loss on financing receivable. Excludes allowance for financing receivable covered under loss sharing agreement.

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Amount of valuation allowance for financing receivables that are expected to be uncollectible that were individually evaluated for impairment.

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Loans and Leases (Allowance For Loan And Lease Losses By Portfolio Segment) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Jan. 01, 2020	Dec. 31, 2019	Mar. 31, 2019
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 209,096	$ 212,353
Provision charged to expense	76,085	8,600
Charge-offs	(10,161)	(13,033)
Recoveries	2,343	3,469
Balance, end of period	209,096	212,353	$ 334,931		$ 209,096	$ 211,389
ALLL, Individually evaluated for impairment			13,012			13,805
ALLL, Collectively evaluated for impairment			321,919			197,584
Loan and lease balances, Individually evaluated for impairment			332,117			274,376
Loan and lease balances, Collectively evaluated for impairment			20,559,407			18,539,914
Loans and leases			20,891,524		20,036,986	18,814,290
Allowance for credit losses on loans and leases					209,096
Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on loans and leases			57,568	$ 266,664		0
Commercial Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	161,669	164,073
Provision charged to expense	71,243	7,990
Charge-offs	(5,574)	(8,810)
Recoveries	564	804
Balance, end of period	161,669	164,073	261,926		161,669	164,057
ALLL, Individually evaluated for impairment			8,235			8,262
ALLL, Collectively evaluated for impairment			253,691			155,795
Loan and lease balances, Individually evaluated for impairment			177,012			133,203
Loan and lease balances, Collectively evaluated for impairment			13,511,409			11,709,564
Loans and leases			13,688,421		12,830,177	11,842,767
Commercial Portfolio Segment [Member] \| Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on loans and leases			34,024			0
Consumer Portfolio Segment [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	47,427	48,280
Provision charged to expense	4,842	610
Charge-offs	(4,587)	(4,223)
Recoveries	1,779	2,665
Balance, end of period	$ 47,427	$ 48,280	73,005		47,427	47,332
ALLL, Individually evaluated for impairment			4,777			5,543
ALLL, Collectively evaluated for impairment			68,228			41,789
Loan and lease balances, Individually evaluated for impairment			155,105			141,173
Loan and lease balances, Collectively evaluated for impairment			7,047,998			6,830,350
Loans and leases			7,203,103		$ 7,206,809	6,971,523
Consumer Portfolio Segment [Member] \| Accounting Standards Update 2016-13 [Member]
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses on loans and leases			$ 23,544			$ 0