SECURITIES AND OTHER INVESTMENTS (Amortized Cost, Gross Unrealized Gains and Losses, and Estimated Fair Values of Investment Securities) (Details) - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	$ 2,942,685	$ 2,615,536
Gross Unrealized Gains	9,292	1,592
Gross Unrealized (Losses)	(343,795)	(385,867)
Total AFS securities, Estimated Fair Value	2,608,182	2,231,261
US Government Agencies Debt Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	65,384	62,367
Gross Unrealized Gains	1,313	1,023
Gross Unrealized (Losses)	(26)	(34)
Total AFS securities, Estimated Fair Value	66,671	63,356
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	600,074	586,865
Gross Unrealized Gains	294	33
Gross Unrealized (Losses)	(111,841)	(111,451)
Total AFS securities, Estimated Fair Value	488,527	475,447
Corporate Bond Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	283,861	261,656
Gross Unrealized Gains	631	7
Gross Unrealized (Losses)	(12,517)	(19,774)
Total AFS securities, Estimated Fair Value	271,975	241,889
Commercial Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	364,248	300,518
Gross Unrealized Gains	1,926	274
Gross Unrealized (Losses)	(39,357)	(43,146)
Total AFS securities, Estimated Fair Value	326,817	257,646
Commercial Mortgage-Backed Securities [Member] | Agency Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	287,747	233,775
Gross Unrealized Gains	1,724	274
Gross Unrealized (Losses)	(37,721)	(41,181)
Total AFS securities, Estimated Fair Value	251,750	192,868
Commercial Mortgage-Backed Securities [Member] | Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	76,501	66,743
Gross Unrealized Gains	202	0
Gross Unrealized (Losses)	(1,636)	(1,965)
Total AFS securities, Estimated Fair Value	75,067	64,778
Residential Mortgage-Backed Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,627,286	1,402,378
Gross Unrealized Gains	5,128	255
Gross Unrealized (Losses)	(180,054)	(211,462)
Total AFS securities, Estimated Fair Value	1,452,360	1,191,171
Residential Mortgage-Backed Securities [Member] | Agency Securities [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,522,319	1,312,538
Gross Unrealized Gains	4,144	114
Gross Unrealized (Losses)	(176,187)	(205,635)
Total AFS securities, Estimated Fair Value	1,350,276	1,107,017
Residential Mortgage-Backed Securities [Member] | Non-agency
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	104,967	89,840
Gross Unrealized Gains	984	141
Gross Unrealized (Losses)	(3,867)	(5,827)
Total AFS securities, Estimated Fair Value	102,084	84,154
Collateralized Securities, Other [Member]
Debt Securities, Available-for-sale Securities, Amortized Cost Basis [Abstract]
Total AFS securities	1,832	1,752
Gross Unrealized Gains	0	0
Gross Unrealized (Losses)	0	0
Total AFS securities, Estimated Fair Value	$ 1,832	$ 1,752