Loans Receivable and Allowance for Credit Losses - Schedule of Composition of Loans Held-for-Investment (Details) - USD ($) $ in Thousands	Jun. 30, 2026	Mar. 31, 2026	Dec. 31, 2025	Jun. 30, 2025	Mar. 31, 2025	Dec. 31, 2024
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	$ 58,963,940		$ 56,878,172
ALLL	(842,056)	$ (835,874)	(809,773)	$ (760,416)	$ (734,856)	$ (702,052)
Loans held-for-investment, net	58,121,884		56,068,399
Net deferred loan fees and net unamortized premiums	13,000		26,000
Commercial Lending
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	41,531,689		39,912,528
Commercial Lending | C&I
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	19,862,701		18,650,755
ALLL	(481,087)	(483,384)	(475,613)	(442,291)	(421,288)	(384,319)
Commercial Lending | CRE
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	15,585,610		15,407,088
ALLL	(231,351)	(231,802)	(221,494)	(212,618)	(212,899)	(218,677)
Commercial Lending | Multifamily residential
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	5,251,556		5,112,328
ALLL	(40,340)	(39,446)	(36,555)	(29,073)	(32,324)	(32,117)
Commercial Lending | Construction and land
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	831,822		742,357
ALLL	(19,968)	(17,170)	(15,468)	(17,856)	(15,199)	(17,497)
Commercial Lending | Total CRE
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	21,668,988		21,261,773
Consumer Lending
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	17,432,251		16,965,644
Consumer Lending | Single-family residential (“SFR”) — Traditional
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	13,818,417		13,692,025
ALLL	(18,826)	(19,230)	(19,040)	(18,711)	(19,281)	(19,413)
Consumer Lending | SFR — Bridge to Home Ownership (“BTHO”)
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	1,517,892		1,310,524
ALLL	(42,422)	(37,653)	(34,423)	(33,286)	(27,648)	(25,403)
Consumer Lending | Home equity loans
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	2,039,285		1,911,897
ALLL	(6,560)	(5,899)	(5,804)	(5,256)	(4,879)	(3,132)
Consumer Lending | Total residential mortgage
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	17,375,594		16,914,446
Consumer Lending | Other consumer
LOANS RECEIVABLE AND ALLOWANCE FOR LOAN LOSSES
Loans held-for-investment	56,657		51,198
ALLL	$ (1,502)	$ (1,290)	$ (1,376)	$ (1,325)	$ (1,338)	$ (1,494)