Loans Receivable and Allowance for Credit Losses - Summary of Activities in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022	Dec. 31, 2022
Allowance for loan losses
Allowance for loan losses, December 31, 2022					$ 595,645
Allowance for loan losses, start of period	$ 635,400	$ 563,270	$ 595,645	$ 541,579
Provision for (reversal of) credit losses on loans	38,136	27,274	80,681	51,995
Gross charge-offs	(21,007)	(13,905)	(32,799)	(26,684)
Gross recoveries	2,861	7,264	6,507	18,363
Total net (charge-offs) recoveries	(18,146)	(6,641)	(26,292)	(8,321)
Foreign currency translation adjustment	133	(1,386)	(539)	(2,736)
Allowance for loan losses, end of period	655,523	582,517	655,523	582,517
Commercial lending \| Commercial and industrial (“C&I”)
Allowance for loan losses
Allowance for loan losses, December 31, 2022					371,700
Allowance for loan losses, start of period	375,333	363,282		338,252
Provision for (reversal of) credit losses on loans	13,006	9,575	17,587	37,867
Gross charge-offs	(7,074)	(6,894)	(16,309)	(18,322)
Gross recoveries	2,279	7,172	5,555	16,688
Total net (charge-offs) recoveries	(4,795)	278	(10,754)	(1,634)
Foreign currency translation adjustment	133	(1,386)	(539)	(2,736)
Allowance for loan losses, end of period	383,677	371,749	383,677	371,749
Commercial lending \| CRE
Allowance for loan losses
Allowance for loan losses, December 31, 2022					149,864
Allowance for loan losses, start of period	168,505	140,245		150,940
Provision for (reversal of) credit losses on loans	12,952	5,299	33,313	(5,013)
Gross charge-offs	(3,466)	(288)	(5,838)	(1,357)
Gross recoveries	49	45	364	731
Total net (charge-offs) recoveries	(3,417)	(243)	(5,474)	(626)
Foreign currency translation adjustment	0	0	0	0
Allowance for loan losses, end of period	178,040	145,301	178,040	145,301
Commercial lending \| Residential loan \| Multifamily residential
Allowance for loan losses
Allowance for loan losses, December 31, 2022					23,373
Allowance for loan losses, start of period	22,938	26,552		14,400
Provision for (reversal of) credit losses on loans	772	5,047	303	16,680
Gross charge-offs	0	(5,938)	0	(5,947)
Gross recoveries	452	19	480	547
Total net (charge-offs) recoveries	452	(5,919)	480	(5,400)
Foreign currency translation adjustment	0	0	0	0
Allowance for loan losses, end of period	24,162	25,680	24,162	25,680
Commercial lending \| Construction and land
Allowance for loan losses
Allowance for loan losses, December 31, 2022					9,109
Allowance for loan losses, start of period	11,325	6,682		15,468
Provision for (reversal of) credit losses on loans	8,302	817	10,507	(8,027)
Gross charge-offs	(10,413)	0	(10,413)	0
Gross recoveries	2	7	13	65
Total net (charge-offs) recoveries	(10,411)	7	(10,400)	65
Foreign currency translation adjustment	0	0	0	0
Allowance for loan losses, end of period	9,216	7,506	9,216	7,506
Consumer lending \| Residential loan \| Single-family residential
Allowance for loan losses
Allowance for loan losses, December 31, 2022					35,564
Allowance for loan losses, start of period	51,513	21,840		17,160
Provision for (reversal of) credit losses on loans	3,353	6,182	19,296	10,569
Gross charge-offs	0	(775)	0	(775)
Gross recoveries	64	16	69	309
Total net (charge-offs) recoveries	64	(759)	69	(466)
Foreign currency translation adjustment	0	0	0	0
Allowance for loan losses, end of period	54,930	27,263	54,930	27,263
Consumer lending \| HELOCs
Allowance for loan losses
Allowance for loan losses, December 31, 2022					4,475
Allowance for loan losses, start of period	4,526	3,220		3,435
Provision for (reversal of) credit losses on loans	(705)	99	(569)	59
Gross charge-offs	(41)	0	(138)	(193)
Gross recoveries	15	5	26	23
Total net (charge-offs) recoveries	(26)	5	(112)	(170)
Foreign currency translation adjustment	0	0	0	0
Allowance for loan losses, end of period	3,795	3,324	3,795	3,324
Consumer lending \| Other consumer
Allowance for loan losses
Allowance for loan losses, December 31, 2022					1,560
Allowance for loan losses, start of period	1,260	1,449		1,924
Provision for (reversal of) credit losses on loans	456	255	244	(140)
Gross charge-offs	(13)	(10)	(101)	(90)
Gross recoveries	0	0	0	0
Total net (charge-offs) recoveries	(13)	(10)	(101)	(90)
Foreign currency translation adjustment	0	0	0	0
Allowance for loan losses, end of period	$ 1,703	$ 1,694	1,703	$ 1,694
Accounting Standards Update 2022-02
Allowance for loan losses
Impact of ASU 2022-02 adoption					6,028
Allowance for loan losses, start of period			$ (6,000)
Accounting Standards Update 2022-02 \| Commercial lending \| Commercial and industrial (“C&I”)
Allowance for loan losses
Impact of ASU 2022-02 adoption					5,683
Accounting Standards Update 2022-02 \| Commercial lending \| CRE
Allowance for loan losses
Impact of ASU 2022-02 adoption					337
Accounting Standards Update 2022-02 \| Commercial lending \| Residential loan \| Multifamily residential
Allowance for loan losses
Impact of ASU 2022-02 adoption					6
Accounting Standards Update 2022-02 \| Commercial lending \| Construction and land
Allowance for loan losses
Impact of ASU 2022-02 adoption					0
Accounting Standards Update 2022-02 \| Consumer lending \| Residential loan \| Single-family residential
Allowance for loan losses
Impact of ASU 2022-02 adoption					1
Accounting Standards Update 2022-02 \| Consumer lending \| HELOCs
Allowance for loan losses
Impact of ASU 2022-02 adoption					1
Accounting Standards Update 2022-02 \| Consumer lending \| Other consumer
Allowance for loan losses
Impact of ASU 2022-02 adoption					$ 0

Financing Receivable Allowance For Credit Loss Excluding Accrued Interest Before Impact of Adoption

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- Definition

Financing Receivable Allowance For Credit Loss Excluding Accrued Interest Impact of Adoption

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Amount excluding accrued interest, of allowance for credit loss on financing receivable. Excludes net investment in lease.

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Amount of foreign currency translation gain (loss) which decreases (increases) allowance for credit loss on financing receivable. Excludes net investment in lease.

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Amount, after recovery, of writeoff of financing receivable, charged against allowance for credit loss.

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Amount of increase in allowance for credit loss on financing receivable from recovery.

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Amount of credit loss expense (reversal of expense) for financing receivable.

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