Amount, after recoveries, of loans and leases that have been written-off.

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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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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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Amount of increase (decrease) in allowance for credit loss on financing receivable.

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Amount, before allowance for credit loss, of financing receivable.

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Amount of expected credit loss for credit exposure on off-balance-sheet commitment, including but not limited to, loan commitment, standby letter of credit, financial guarantee not accounted for as insurance. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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Amount of expense (reversal of expense) for expected credit loss for off-balance sheet credit exposure. Excludes off-balance sheet credit exposure accounted for as insurance and instrument accounted for under derivatives and hedging.

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Amount of expense related to estimated loss from loan and lease transactions.

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ALLOWANCE FOR CREDIT LOSSES FOR LOANS AND FINANCE LEASES - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020	Dec. 31, 2019
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans and finance leases	$ 288,360	$ 384,718	$ 288,360	$ 384,718	$ 324,958	$ 385,887	$ 319,297	$ 155,139
Increase (decrease) in ACL			(97,600)
Loans and finance leases	(8,734)	48,078	(49,479)	158,531
ACL for unfunded loan commitments and standby letters of credit	1,759	6,281	1,759	6,281	2,730	5,105	7,084	0
Provision (release) for credit losses on unfunded loan commitments and standby letters of credit	(971)	(803)	(3,346)	2,359
Loans held for investment	11,140,582		11,140,582			11,777,289
Residential Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans and finance leases	83,226	131,781	83,226	131,781	112,882	120,311	111,450	44,806
Increase (decrease) in ACL			(37,100)
Loans and finance leases	(6,206)	9,875	(9,556)	32,255
Net charge-offs			27,500
Loans held for investment	3,095,015		3,095,015			3,521,954
Commercial Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Increase (decrease) in ACL			(46,600)
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans and finance leases	33,348	42,909	33,348	42,909	37,470	37,944	38,310	15,198
Loans and finance leases	(4,449)	2,839	(10,187)	11,225
Loans held for investment	2,932,712		2,932,712			3,202,590
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans and finance leases	67,406	75,726	67,406	75,726	72,452	109,342	49,435	39,194
Loans and finance leases	(4,660)	19,672	(40,779)	49,278
Loans held for investment	2,136,502		2,136,502			2,230,602
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans and finance leases	5,319	10,241	5,319	10,241	4,757	5,380	7,800	2,370
Loans and finance leases	527	2,405	(125)	7,068
Loans held for investment	170,208		170,208			212,500
Consumer Portfolio Segment [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Allowance for credit losses on loans and finance leases	99,061	124,061	99,061	124,061	$ 97,397	112,910	$ 112,302	$ 53,571
Increase (decrease) in ACL			(13,800)
Loans and finance leases	6,054	$ 13,287	11,168	$ 58,705
Net charge-offs			25,000
Loans held for investment	2,806,145		2,806,145			2,609,643
COVID-19 [Member] \| Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member] \| US Government Insured Loan Program [Member]
Financing Receivable Allowance For Credit Losses [Line Items]
Loans held for investment	$ 218,400		$ 218,400			$ 406,000