Loans Receivable and Allowance for Credit Losses - Summary of Activities in Allowance for Loan Losses (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	$ 541,579	$ 619,983	$ 358,287
Provision for (reversal of) credit losses	74,767	(28,954)	198,691
Gross charge-offs	(37,920)	(66,592)	(81,837)
Gross recoveries	19,461	16,614	18,672
Total net (charge-offs) recoveries	(18,459)	(49,978)	(63,165)
Foreign currency translation adjustment	(2,242)	528	1,012
Allowance for loan losses, balance at the end of the period	595,645	541,579	619,983	$ 358,287
Accounting Standards Update [Extensible List]				Accounting Standards Update 2016-13
Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			125,158
Allowance for loan losses, balance at the end of the period				$ 125,158
Commercial Lending | C&I
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	338,252	398,040	238,376
Provision for (reversal of) credit losses	37,604	(39,732)	145,212
Gross charge-offs	(18,738)	(32,490)	(66,225)
Gross recoveries	16,824	11,906	5,428
Total net (charge-offs) recoveries	(1,914)	(20,584)	(60,797)
Foreign currency translation adjustment	(2,242)	528	1,012
Allowance for loan losses, balance at the end of the period	371,700	338,252	398,040	238,376
Commercial Lending | C&I | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			74,237
Allowance for loan losses, balance at the end of the period				74,237
Commercial Lending | CRE
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	150,940	163,791	40,509
Provision for (reversal of) credit losses	8,212	14,282	55,864
Gross charge-offs	(10,871)	(28,430)	(15,206)
Gross recoveries	1,583	1,297	10,455
Total net (charge-offs) recoveries	(9,288)	(27,133)	(4,751)
Foreign currency translation adjustment	0	0	0
Allowance for loan losses, balance at the end of the period	149,864	150,940	163,791	40,509
Commercial Lending | CRE | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			72,169
Allowance for loan losses, balance at the end of the period				72,169
Commercial Lending | Residential loan | Multifamily
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	14,400	27,573	22,826
Provision for (reversal of) credit losses	15,651	(15,076)	10,879
Gross charge-offs	(7,237)	(130)	0
Gross recoveries	559	2,033	1,980
Total net (charge-offs) recoveries	(6,678)	1,903	1,980
Foreign currency translation adjustment	0	0	0
Allowance for loan losses, balance at the end of the period	23,373	14,400	27,573	22,826
Commercial Lending | Residential loan | Multifamily | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			(8,112)
Allowance for loan losses, balance at the end of the period				(8,112)
Commercial Lending | Construction and land
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	15,468	10,239	19,404
Provision for (reversal of) credit losses	(6,433)	7,576	644
Gross charge-offs	0	(2,954)	0
Gross recoveries	74	607	80
Total net (charge-offs) recoveries	74	(2,347)	80
Foreign currency translation adjustment	0	0	0
Allowance for loan losses, balance at the end of the period	9,109	15,468	10,239	19,404
Commercial Lending | Construction and land | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			(9,889)
Allowance for loan losses, balance at the end of the period				(9,889)
Consumer Lending | Residential loan | Single-family
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	17,160	15,520	28,527
Provision for (reversal of) credit losses	18,867	1,965	(9,922)
Gross charge-offs	(775)	(1,046)	0
Gross recoveries	312	721	585
Total net (charge-offs) recoveries	(463)	(325)	585
Foreign currency translation adjustment	0	0	0
Allowance for loan losses, balance at the end of the period	35,564	17,160	15,520	28,527
Consumer Lending | Residential loan | Single-family | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			(3,670)
Allowance for loan losses, balance at the end of the period				(3,670)
Consumer Lending | HELOCs
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	3,435	2,690	5,265
Provision for (reversal of) credit losses	1,124	745	(605)
Gross charge-offs	(193)	(45)	(221)
Gross recoveries	109	45	49
Total net (charge-offs) recoveries	(84)	0	(172)
Foreign currency translation adjustment	0	0	0
Allowance for loan losses, balance at the end of the period	4,475	3,435	2,690	5,265
Consumer Lending | HELOCs | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			(1,798)
Allowance for loan losses, balance at the end of the period				(1,798)
Consumer Lending | Other consumer
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	1,924	2,130	3,380
Provision for (reversal of) credit losses	(258)	1,286	(3,381)
Gross charge-offs	(106)	(1,497)	(185)
Gross recoveries	0	5	95
Total net (charge-offs) recoveries	(106)	(1,492)	(90)
Foreign currency translation adjustment	0	0	0
Allowance for loan losses, balance at the end of the period	$ 1,560	$ 1,924	2,130	3,380
Consumer Lending | Other consumer | Cumulative Effect, Period of Adoption, Adjustment | Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period			$ 2,221
Allowance for loan losses, balance at the end of the period				$ 2,221