Loans Receivable and Allowance for Credit Losses (Summary of Activities in Allowance for Loan Losses) (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 01, 2019	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Losses
Accounting Standards Update [Extensible List]	Accounting Standards Update 2016-02		Accounting Standards Update 2016-13		Accounting Standards Update 2016-13
Allowance for loan losses
Allowance for loan losses, balance at the beginning of the period	$ 311,322	$ 619,983	$ 358,287	$ 311,322
(Reversal of ) provision for credit losses on loans		(28,937)	198,691	100,093
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(66,592)	(81,837)	(75,067)
Gross recoveries		16,614	18,672	22,264
Total net (charge-offs) recoveries		(49,978)	(63,165)	(52,803)
Foreign currency translation adjustment		511	1,012	(325)
Allowance for loan losses, balance at the end of the period		541,579	619,983	358,287	$ 311,322
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
Net Charge-Off/Recoveries [Abstract]
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	189,117	398,040	238,376	189,117
(Reversal of ) provision for credit losses on loans		(39,715)	145,212	109,068
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(32,490)	(66,225)	(73,985)
Gross recoveries		11,906	5,428	14,501
Total net (charge-offs) recoveries		(20,584)	(60,797)	(59,484)
Foreign currency translation adjustment		511	1,012	(325)
Allowance for loan losses, balance at the end of the period		338,252	398,040	238,376	189,117
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
Net Charge-Off/Recoveries [Abstract]
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	40,666	163,791	40,509	40,666
(Reversal of ) provision for credit losses on loans		14,282	55,864	(4,345)
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(28,430)	(15,206)	(1,021)
Gross recoveries		1,297	10,455	5,209
Total net (charge-offs) recoveries		(27,133)	(4,751)	4,188
Foreign currency translation adjustment		0	0	0
Allowance for loan losses, balance at the end of the period		150,940	163,791	40,509	40,666
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
Net Charge-Off/Recoveries [Abstract]
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	19,885	27,573	22,826	19,885
(Reversal of ) provision for credit losses on loans		(15,076)	10,879	1,085
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(130)	0	0
Gross recoveries		2,033	1,980	1,856
Total net (charge-offs) recoveries		1,903	1,980	1,856
Foreign currency translation adjustment		0	0	0
Allowance for loan losses, balance at the end of the period		14,400	27,573	22,826	19,885
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)
Net Charge-Off/Recoveries [Abstract]
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	20,290	10,239	19,404	20,290
(Reversal of ) provision for credit losses on loans		7,576	644	(1,422)
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(2,954)	0	0
Gross recoveries		607	80	536
Total net (charge-offs) recoveries		(2,347)	80	536
Foreign currency translation adjustment		0	0	0
Allowance for loan losses, balance at the end of the period		15,468	10,239	19,404	20,290
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)
Net Charge-Off/Recoveries [Abstract]
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	31,340	15,520	28,527	31,340
(Reversal of ) provision for credit losses on loans		1,965	(9,922)	(2,938)
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(1,046)	0	(11)
Gross recoveries		721	585	136
Total net (charge-offs) recoveries		(325)	585	125
Foreign currency translation adjustment		0	0	0
Allowance for loan losses, balance at the end of the period		17,160	15,520	28,527	31,340
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)
Net Charge-Off/Recoveries [Abstract]
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	5,774	2,690	5,265	5,774
(Reversal of ) provision for credit losses on loans		745	(605)	(516)
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(45)	(221)	0
Gross recoveries		45	49	7
Total net (charge-offs) recoveries		0	(172)	7
Foreign currency translation adjustment		0	0	0
Allowance for loan losses, balance at the end of the period		3,435	2,690	5,265	5,774
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)
Net Charge-Off/Recoveries [Abstract]
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	$ 4,250	2,130	3,380	4,250
(Reversal of ) provision for credit losses on loans		1,286	(3,381)	(839)
Net Charge-Off/Recoveries [Abstract]
Gross charge-offs		(1,497)	(185)	(50)
Gross recoveries		5	95	19
Total net (charge-offs) recoveries		(1,492)	(90)	(31)
Foreign currency translation adjustment		0	0	0
Allowance for loan losses, balance at the end of the period		$ 1,924	2,130	3,380	$ 4,250
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
Net Charge-Off/Recoveries [Abstract]
Allowance for loan losses, balance at the end of the period				$ 2,221