Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net (loss) earnings	$ (1,899,137)	$ 423,613	$ 606,959
Goodwill impairment	1,376,736	29,000	0
Depreciation and amortization	52,691	53,595	52,195
Amortization of net premiums on investment securities	37,488	52,749	44,197
Intangible asset amortization	11,419	13,576	12,734
Amortization of operating lease ROU assets	27,176	30,228	30,406
Provision for credit losses	52,000	24,500	(162,000)
Gain on sale of foreclosed assets, net	(586)	(3,470)	(406)
Provision for losses on foreclosed assets	1,992	29	14
Loss (gain) on sale of loans and leases, net	161,346	(518)	(1,733)
(Gain) loss on disposal of premises and equipment	(571)	104	74
Loss (gain) on sale of securities, net	442,413	50,321	(1,615)
Gain on BOLI death benefits	(416)	0	(491)
credit-linked notes, net	5,629	(1,089)	(1,134)
LOCOM HFS Adjustment	8,461	0	0
Increase in other assets	(214,614)	(83,666)	(97,181)
Increase (decrease) in accrued interest payable and other liabilities	45,044	78,231	(11,286)
Net cash provided by operating activities	135,768	701,972	502,956
Cash flows from investing activities:
Cash acquired in acquisitions, net of cash consideration paid	335,319	0	3,757,122
Net decrease (increase) in loans and leases	464,057	(5,816,608)	(3,925,829)
Proceeds from sales of loans and leases	8,524,063	72,214	144,550
Proceeds from maturities and paydowns of securities available-for-sale	261,042	658,719	847,472
Proceeds from sales of securities available-for-sale	3,028,011	2,013,094	367,348
Purchases of securities available-for-sale	(13,439)	(380,251)	(6,863,950)
Proceeds from maturities and paydowns of securities held-to-maturity	1,353	851	0
Net (purchases) redemptions of Federal Home Loan Bank stock	(31,852)	(17,040)	0
Proceeds from sales of foreclosed assets	17,137	19,247	2,638
Purchases of premises and equipment, net	(15,219)	(20,128)	(17,262)
Proceeds from sales of premises and equipment	9,018	11	95
Proceeds from BOLI death benefits	3,946	555	4,143
Net decrease (increase) in equipment leased to others under operating leases	25,709	(100,734)	(30,786)
Net cash provided by (used in) investing activities	12,609,145	(3,570,070)	(5,714,459)
Cash flows from financing activities:
Net (decrease) increase in noninterest-bearing deposits	(5,722,546)	(3,330,776)	3,726,157
Net (decrease) increase in interest-bearing deposits	(4,359,678)	2,269,353	2,170,769
Net increase (decrease) in borrowings	185,784	1,763,119	(55,210)
Net proceeds from stock issuance	382,900	0	0
Proceeds from Issuance of Common Stock, Dividend Reinvestment Plan	69	0	0
Restricted stock surrendered		(9,531)	(8,505)
Common stock dividends paid		(120,256)	(119,443)
Net cash (used in) provided by financing activities	(9,607,559)	1,051,086	6,108,076
Net increase (decrease) in cash and cash equivalents	3,137,354	(1,817,012)	896,573
Cash and cash equivalents, beginning of year	2,240,222	4,057,234	3,160,661
Cash and cash equivalents, end of year	5,377,576	2,240,222	4,057,234
Supplemental disclosures of cash flow information:
Cash paid for interest	1,063,981	238,377	53,446
Cash (received) paid for income taxes	(68,168)	97,254	136,015
Loans transferred to foreclosed assets	20,915	7,985	1,062
Transfers from loans held for investment to loans held for sale	3,162,615	76,253	25,554
Loan, Transfer from Held-for-Sale to Held-in-Portfolio	513,914	0	0
Transfer of securities available-for-sale to held-to-maturity	0	2,260,407	0
Fair value of assets acquired	38,534,064	41,228,936
Liabilities assumed	35,143,299	37,278,405
Pacific Western Bank
Supplemental disclosures of cash flow information:
Fair value of assets acquired	8,206,850
Business Combination, Consideration Transferred	(663,004)
Parent [Member]
Cash flows from operating activities:
Earned stock compensation	28,697	34,769	32,223
Increase in other assets	(466,018)	(323,852)	(67,242)
Cash flows from investing activities:
Cash acquired in acquisitions, net of cash consideration paid	26,310		0
Cash flows from financing activities:
Net proceeds from subordinated notes offering	0	0	394,308
Net proceeds from stock issuance	382,900	0	0
Net proceeds from preferred stock offering	0	498,516	0
Restricted stock surrendered	(5,419)	(9,531)	(8,505)
Preferred stock dividends paid	(39,788)	(19,339)	0
Common stock dividends paid	(48,881)	(120,256)	$ (119,443)
Supplemental disclosures of cash flow information:
Fair value of assets acquired	3,805,364	4,090,143
Liabilities assumed	$ 414,599	$ 139,612