INVESTMENT SECURITIES - Schedule of Amortized Cost and Estimated Fair Value of Available-for-Sale and Held-to-Maturity Investment Securities (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Available-for-Sale Debt Securities
Amortized Cost	$ 4,834,550,000	$ 5,249,882,000
Gross Unrealized Gain	0	34,626,000
Gross Unrealized Loss	741,490,000	79,197,000
Allowance for Credit Losses	0	0
Fair Value	4,093,060,000	5,205,311,000
Held-to-Maturity Debt Securities
Investment securities, held to maturity, net	1,111,629,000	90,646,000
Gross Unrealized Gain	534,000	3,489,000
Gross Unrealized Loss	72,049,000	0
Allowance for Credit Losses	10,000	4,000
Fair Value	1,040,104,000	94,131,000
Available for sale securities transfers to held to maturity unrealized gains	(142,800,000)
Collateralized mortgage obligation (CMO)
Available-for-Sale Debt Securities
Amortized Cost	608,834,000	586,830,000
Gross Unrealized Gain	0	3,569,000
Gross Unrealized Loss	102,454,000	14,633,000
Allowance for Credit Losses	0	0
Fair Value	506,380,000	575,766,000
Fannie Mae (FNMA) mortgage-backed securities (MBS)
Available-for-Sale Debt Securities
Amortized Cost	3,823,036,000	4,275,307,000
Gross Unrealized Gain	0	24,170,000
Gross Unrealized Loss	572,778,000	53,793,000
Allowance for Credit Losses	0	0
Fair Value	3,250,258,000	4,245,684,000
Held-to-Maturity Debt Securities
Investment securities, held to maturity, net	909,498,000
Gross Unrealized Gain	0
Gross Unrealized Loss	68,677,000
Allowance for Credit Losses	0
Fair Value	840,821,000
Freddie Mac (FHLMC) MBS
Available-for-Sale Debt Securities
Amortized Cost	135,554,000	139,708,000
Gross Unrealized Gain	0	6,336,000
Gross Unrealized Loss	13,555,000	516,000
Allowance for Credit Losses	0	0
Fair Value	121,999,000	145,528,000
Ginnie Mae (GNMA) MBS
Available-for-Sale Debt Securities
Amortized Cost	39,116,000	17,456,000
Gross Unrealized Gain	0	551,000
Gross Unrealized Loss	2,978,000	71,000
Allowance for Credit Losses	0	0
Fair Value	36,138,000	17,936,000
Government-sponsored enterprises (GSE) agency notes
Available-for-Sale Debt Securities
Amortized Cost	228,010,000	230,581,000
Gross Unrealized Gain	0	0
Gross Unrealized Loss	49,725,000	10,184,000
Allowance for Credit Losses	0	0
Fair Value	178,285,000	220,397,000
State and political subdivisions
Held-to-Maturity Debt Securities
Investment securities, held to maturity, net	201,631,000	90,146,000
Gross Unrealized Gain	532,000	3,489,000
Gross Unrealized Loss	3,372,000	0
Allowance for Credit Losses	10,000	4,000	$ 6,000
Fair Value	198,781,000	93,631,000
Available for sale securities transfers to held to maturity unrealized gains		200,000
Foreign bonds
Held-to-Maturity Debt Securities
Investment securities, held to maturity, net	500,000	500,000
Gross Unrealized Gain	2,000	0
Gross Unrealized Loss	0	0
Allowance for Credit Losses	0	0
Fair Value	$ 502,000	$ 500,000

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).

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