SECURITIES (Schedule of Securities) (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Schedule of Securities [Line Items]
Debt Securities, Trading, Amortized Cost	$ 27,203,000	$ 27,203,000
Securities—trading	27,354,000	26,981,000
Debt Securities, Available-for-sale, Amortized Cost, Total	3,315,213,000	3,653,160,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	6,139,000	36,927,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	173,805,000	51,094,000
Securities—available-for-sale	3,147,547,000	3,638,993,000
Held-to-maturity Securities, Amortized Cost	1,015,942,000	521,355,000
Held-to-maturity Securities, Gross Unrealized Gains	2,445,000	21,917,000
Held-to-maturity Securities, Gross Unrealized Losses	49,847,000	1,419,000
Securities—held-to-maturity	968,540,000	541,853,000
Debt Securities, Held-to-maturity, Allowance for Credit Loss	420,000	(433,000)
debt securities, held-to-maturity, accrued interest receivable	3,800,000	3,300,000
Debt Securities, Available-for-Sale, Accrued Interest Receivable	10,100,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	0	0
U.S. Government and agency obligations
Schedule of Securities [Line Items]
Debt Securities, Available-for-sale, Amortized Cost, Total	194,774,000	201,101,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	176,000	852,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	756,000	621,000
Securities—available-for-sale	194,194,000	201,332,000
Held-to-maturity Securities, Amortized Cost	315,000	316,000
Held-to-maturity Securities, Gross Unrealized Gains	2,000	3,000
Held-to-maturity Securities, Gross Unrealized Losses	2,000	0
Securities—held-to-maturity	315,000	319,000
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0	$ 0	$ 0
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	0	0
Municipal bonds
Schedule of Securities [Line Items]
Debt Securities, Available-for-sale, Amortized Cost, Total	285,235,000	293,761,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	3,267,000	15,171,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	16,238,000	320,000
Securities—available-for-sale	272,264,000	308,612,000
Held-to-maturity Securities, Amortized Cost	442,328,000	420,555,000
Held-to-maturity Securities, Gross Unrealized Gains	2,304,000	20,743,000
Held-to-maturity Securities, Gross Unrealized Losses	28,252,000	1,393,000
Securities—held-to-maturity	416,380,000	439,905,000
Debt Securities, Held-to-maturity, Allowance for Credit Loss	191,000	203,000	61,000	59,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	0	0
Corporate bonds
Schedule of Securities [Line Items]
Debt Securities, Trading, Amortized Cost	27,203,000	27,203,000
Securities—trading	27,354,000	26,981,000
Debt Securities, Available-for-sale, Amortized Cost, Total	119,396,000	114,427,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	383,000	3,103,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	2,196,000	183,000
Securities—available-for-sale	117,583,000	117,347,000
Held-to-maturity Securities, Amortized Cost	3,059,000	3,092,000
Held-to-maturity Securities, Gross Unrealized Gains	0	0
Held-to-maturity Securities, Gross Unrealized Losses	18,000	3,000
Securities—held-to-maturity	3,041,000	3,089,000
Debt Securities, Held-to-maturity, Allowance for Credit Loss	229,000	230,000	37,000	35,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	0	0
Mortgage-backed or related securities
Schedule of Securities [Line Items]
Debt Securities, Available-for-sale, Amortized Cost, Total	2,509,530,000	2,837,480,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	2,202,000	17,749,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	153,899,000	49,961,000
Securities—available-for-sale	2,357,833,000	2,805,268,000
Held-to-maturity Securities, Amortized Cost	570,240,000	97,392,000
Held-to-maturity Securities, Gross Unrealized Gains	139,000	1,171,000
Held-to-maturity Securities, Gross Unrealized Losses	21,575,000	23,000
Securities—held-to-maturity	548,804,000	98,540,000
Debt Securities, Held-to-maturity, Allowance for Credit Loss	0	0	$ 0	$ 0
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	0	0
Asset-backed securities
Schedule of Securities [Line Items]
Debt Securities, Available-for-sale, Amortized Cost, Total	206,278,000	206,391,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Gain, before Tax	111,000	52,000
Debt Securities, Available-for-sale, Accumulated Gross Unrealized Loss, before Tax	716,000	9,000
Securities—available-for-sale	205,673,000	206,434,000
Debt Securities, Available-for-sale, Unrealized Loss Position, Number of Positions	$ 0	$ 0