Loans Receivable and Allowance for Credit Losses - Loan Purchases, Sales and Transfers (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	$ 112,363	$ 163,780	$ 463,769	$ 411,416
Loans transferred from held-for-sale to held-for-investment			631
Sales	127,165	169,830	446,753	427,427
Purchases	57,662	203,291	599,422	745,717
Writeoff	8,700	3,600	8,900	4,900
Net gains on sales of loans	2,129	3,329	5,968	6,601
C&I and CRE \| Originated
Loans Receivable and Allowance for Credit Losses
Sales	86,200	143,300	253,900	341,900
Loans sold in secondary market \| Purchased
Loans Receivable and Allowance for Credit Losses
Sales	40,900	26,500	192,900	85,500
Commercial lending \| Commercial and industrial (“C&I”)
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	59,069	117,196	378,841	327,781
Loans transferred from held-for-sale to held-for-investment			0
Sales	87,597	118,851	375,100	329,233
Purchases	56,507	65,354	361,169	310,447
Commercial lending \| Commercial real estate (“CRE”)
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	33,616	24,120	65,250	61,171
Loans transferred from held-for-sale to held-for-investment			0
Sales	33,616	24,120	65,250	61,171
Purchases	0	0	0	0
Commercial lending \| Real estate loan \| Multifamily residential
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	14,500		14,500	0
Loans transferred from held-for-sale to held-for-investment			0
Sales	0		0	0
Purchases	0		0	370
Commercial lending \| Construction and land
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale		17,226		17,226
Sales		19,900		19,900
Purchases		0		0
Consumer lending \| Real estate loan \| Single-family residential
Loans Receivable and Allowance for Credit Losses
Loans transferred from held-for-investment to held-for-sale	5,178	5,238	5,178	5,238
Loans transferred from held-for-sale to held-for-investment			631
Sales	5,952	6,959	6,403	17,123
Purchases	$ 1,155	$ 137,937	$ 238,253	$ 434,900

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

+ References

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Amount of increase in financing receivable from purchase. Excludes net investment in lease.

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Amount of decrease in financing receivable from sale and reclassification to held-for-sale. Excludes net investment in lease.

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The net gain (loss) resulting from a sale of loans, including adjustments to record loans classified as held-for-sale at the lower-of-cost-or-market and fair value adjustments to loan held for investment purposes.

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