SECURITIES AND OTHER INVESTMENTS (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	$ 4,595,098	$ 2,844,763
Gross Unrealized Gains	16,587	3,378
Gross Unrealized (Losses)	(344,162)	(405,975)
Total AFS securities, Estimated Fair Value	4,267,523	2,442,166
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	128,592	65,650
Gross Unrealized Gains	723	390
Gross Unrealized (Losses)	(34)	(27)
Total AFS securities, Estimated Fair Value	129,281	66,013
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	598,767	597,956
Gross Unrealized Gains	186	84
Gross Unrealized (Losses)	(117,438)	(129,703)
Total AFS securities, Estimated Fair Value	481,515	468,337
Corporate Bond Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	250,663	253,526
Gross Unrealized Gains	686	505
Gross Unrealized (Losses)	(5,194)	(9,319)
Total AFS securities, Estimated Fair Value	246,155	244,712
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	462,479	347,501
Gross Unrealized Gains	1,370	352
Gross Unrealized (Losses)	(42,929)	(46,788)
Total AFS securities, Estimated Fair Value	420,920	301,065
Commercial Mortgage-Backed Securities [Member] \| Agency Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	359,154	285,949
Gross Unrealized Gains	1,148	348
Gross Unrealized (Losses)	(40,826)	(44,678)
Total AFS securities, Estimated Fair Value	319,476	241,619
Commercial Mortgage-Backed Securities [Member] \| Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	103,325	61,552
Gross Unrealized Gains	222	4
Gross Unrealized (Losses)	(2,103)	(2,110)
Total AFS securities, Estimated Fair Value	101,444	59,446
Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	3,152,665	1,578,270
Gross Unrealized Gains	13,622	2,047
Gross Unrealized (Losses)	(178,567)	(220,138)
Total AFS securities, Estimated Fair Value	2,987,720	1,360,179
Residential Mortgage-Backed Securities [Member] \| Agency Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	2,968,326	1,478,648
Gross Unrealized Gains	12,772	1,375
Gross Unrealized (Losses)	(175,713)	(216,754)
Total AFS securities, Estimated Fair Value	2,805,385	1,263,269
Residential Mortgage-Backed Securities [Member] \| Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	184,339	99,622
Gross Unrealized Gains	850	672
Gross Unrealized (Losses)	(2,854)	(3,384)
Total AFS securities, Estimated Fair Value	182,335	96,910
Collateralized Securities, Other [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,932	1,860
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Total AFS securities, Estimated Fair Value	$ 1,932	$ 1,860

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (b)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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- Definition

Amount, before tax, of unrealized loss in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 320
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 2
-Subparagraph (c)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147481800/320-10-50-2

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Amortized cost excluding accrued interest, before allowance for credit loss, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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Amount excluding accrued interest, of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Topic 326
-SubTopic 30
-Name Accounting Standards Codification
-Section 45
-Paragraph 1
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147479130/326-30-45-1

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