LOANS HELD FOR INVESTMENT - Loan Portfolio Held for Investment (Detail) - USD ($) $ in Thousands	Sep. 30, 2020	Jun. 30, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Dec. 31, 2018
Loans held for investment	$ 11,847,275		$ 9,002,205
Allowance for credit losses on loans and finance leases	(384,718)	$ (319,297)	(155,139)	$ (165,575)	$ (172,011)	$ (196,362)
Loans, net of allowance for credit losses of $384,718 (2019 - $155,139)	11,462,557		8,847,066
Residential Portfolio Segment [Member]
Loans held for investment	3,636,713		2,933,773
Allowance for credit losses on loans and finance leases	(131,781)	(111,450)	(44,806)	(46,032)	(48,284)	(50,794)
Commercial Portfolio Segment [Member] \| Commercial And Industrial Sector [Member]
Loans held for investment	3,226,843		2,230,876
Allowance for credit losses on loans and finance leases	(42,909)	(38,310)	(15,198)	(17,618)	(21,644)	(32,546)
Commercial Portfolio Segment [Member] \| Mortgage Receivable [Member]
Loans held for investment	2,220,277		1,444,586
Allowance for credit losses on loans and finance leases	(75,726)	(49,435)	(39,194)	(44,848)	(46,373)	(55,581)
Commercial Portfolio Segment [Member] \| Construction Loans [Member]
Loans held for investment	191,356		111,317
Allowance for credit losses on loans and finance leases	(10,241)	(7,800)	(2,370)	(3,059)	(3,026)	(3,592)
Consumer Portfolio Segment [Member]
Loans held for investment	2,572,086		2,281,653
Allowance for credit losses on loans and finance leases	$ (124,061)	$ (112,302)	$ (53,571)	$ (54,018)	$ (52,684)	$ (53,849)

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

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Amount after allowance and deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements and loans held for sale.

+ References

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

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