SECURITIES (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	$ 3,204,361	$ 3,448,784
Gross Unrealized Gains	293	65,198
Gross Unrealized (Losses)	(462,838)	(32,332)
Total AFS securities, Estimated Fair Value	2,741,816	3,481,650
U.S. government and agency securities
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	70,196	73,830
Gross Unrealized Gains	0	179
Gross Unrealized (Losses)	(8,253)	(160)
Total AFS securities, Estimated Fair Value	61,943	73,849
Obligations of states and political subdivisions
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	959,999	971,126
Gross Unrealized Gains	137	39,343
Gross Unrealized (Losses)	(152,701)	(2,073)
Total AFS securities, Estimated Fair Value	807,435	1,008,396
Corporate and other bonds
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	243,979	150,201
Gross Unrealized Gains	0	3,353
Gross Unrealized (Losses)	(17,599)	(178)
Total AFS securities, Estimated Fair Value	226,380	153,376
Commercial
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	349,598	468,893
Gross Unrealized Gains	75	6,900
Gross Unrealized (Losses)	(43,512)	(4,636)
Total AFS securities, Estimated Fair Value	306,161	471,157
Commercial | Agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	250,186	361,806
Gross Unrealized Gains	75	6,761
Gross Unrealized (Losses)	(39,268)	(4,215)
Total AFS securities, Estimated Fair Value	210,993	364,352
Commercial | Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	99,412	107,087
Gross Unrealized Gains	0	139
Gross Unrealized (Losses)	(4,244)	(421)
Total AFS securities, Estimated Fair Value	95,168	106,805
Residential
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,578,925	1,783,094
Gross Unrealized Gains	81	15,423
Gross Unrealized (Losses)	(240,773)	(25,285)
Total AFS securities, Estimated Fair Value	1,338,233	1,773,232
Residential | Agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,510,110	1,691,651
Gross Unrealized Gains	81	15,180
Gross Unrealized (Losses)	(233,961)	(24,337)
Total AFS securities, Estimated Fair Value	1,276,230	1,682,494
Residential | Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	68,815	91,443
Gross Unrealized Gains	0	243
Gross Unrealized (Losses)	(6,812)	(948)
Total AFS securities, Estimated Fair Value	62,003	90,738
Other securities
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,664	1,640
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Total AFS securities, Estimated Fair Value	$ 1,664	$ 1,640