SECURITIES AND OTHER INVESTMENTS (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	$ 2,976,422	$ 2,615,536
Gross Unrealized Gains	1,797	1,592
Gross Unrealized (Losses)	(422,496)	(385,867)
Total AFS securities, Estimated Fair Value	2,555,723	2,231,261
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	65,328	62,367
Gross Unrealized Gains	0	1,023
Gross Unrealized (Losses)	(78)	(34)
Total AFS securities, Estimated Fair Value	65,250	63,356
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	600,467	586,865
Gross Unrealized Gains	9	33
Gross Unrealized (Losses)	(131,091)	(111,451)
Total AFS securities, Estimated Fair Value	469,385	475,447
Corporate Bond Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	289,123	261,656
Gross Unrealized Gains	250	7
Gross Unrealized (Losses)	(17,569)	(19,774)
Total AFS securities, Estimated Fair Value	271,804	241,889
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	369,162	300,518
Gross Unrealized Gains	387	274
Gross Unrealized (Losses)	(45,853)	(43,146)
Total AFS securities, Estimated Fair Value	323,696	257,646
Commercial Mortgage-Backed Securities [Member] | Agency Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	290,895	233,775
Gross Unrealized Gains	377	274
Gross Unrealized (Losses)	(43,817)	(41,181)
Total AFS securities, Estimated Fair Value	247,455	192,868
Commercial Mortgage-Backed Securities [Member] | Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	78,267	66,743
Gross Unrealized Gains	10	0
Gross Unrealized (Losses)	(2,036)	(1,965)
Total AFS securities, Estimated Fair Value	76,241	64,778
Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,650,537	1,402,378
Gross Unrealized Gains	1,151	255
Gross Unrealized (Losses)	(227,905)	(211,462)
Total AFS securities, Estimated Fair Value	1,423,783	1,191,171
Residential Mortgage-Backed Securities [Member] | Agency Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,547,394	1,312,538
Gross Unrealized Gains	762	114
Gross Unrealized (Losses)	(223,054)	(205,635)
Total AFS securities, Estimated Fair Value	1,325,102	1,107,017
Residential Mortgage-Backed Securities [Member] | Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	103,143	89,840
Gross Unrealized Gains	389	141
Gross Unrealized (Losses)	(4,851)	(5,827)
Total AFS securities, Estimated Fair Value	98,681	84,154
Collateralized Securities, Other [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,805	1,752
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Total AFS securities, Estimated Fair Value	$ 1,805	$ 1,752