FAIR VALUE MEASUREMENT AND DISCLOSURE (Summary of Financial Assets and Liabilities Measured at Fair Value on Recurring Basis) (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Financial assets:
Trading securities	$ 4,124	$ 4,428
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	1,421,809	1,507,486
Loans held for sale	6,818	5,786
Financial liabilities:
Debt Securities, Trading	4,124	4,428
Obligations of U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	7,670	8,344
Obligations of states and political subdivisions
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	111,956	117,478
Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	960,838	1,000,257
Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	319,891	358,849
Fair Value, Measurements, Recurring
Financial assets:
Trading securities	4,124	4,428
Loans held for sale	6,705	5,815
Financial liabilities:
Debt Securities, Trading	4,124	4,428
Fair Value, Measurements, Recurring | Obligations of U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	7,670	8,344
Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	111,956	117,478
Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	960,838	1,000,257
Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	319,891	358,849
Fair Value, Measurements, Recurring | Corporate Bond Securities [Member]
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	21,454	22,558
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring
Financial assets:
Trading securities	4,124	4,428
Loans held for sale	0	0
Financial liabilities:
Debt Securities, Trading	4,124	4,428
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Obligations of U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring | Corporate Bond Securities [Member]
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring
Financial assets:
Trading securities	0	0
Loans held for sale	6,705	5,815
Financial liabilities:
Debt Securities, Trading	0	0
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Obligations of U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	7,670	8,344
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	111,956	117,478
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	960,838	1,000,257
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	319,891	358,849
Observable Market Data (Level 2) | Fair Value, Measurements, Recurring | Corporate Bond Securities [Member]
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	21,454	22,558
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring
Financial assets:
Trading securities	0	0
Loans held for sale	0	0
Financial liabilities:
Debt Securities, Trading	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Obligations of U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Obligations of states and political subdivisions
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Mortgage-backed securities issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Collateralized mortgage obligations issued or guaranteed by U.S. government-sponsored enterprises
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring | Corporate Bond Securities [Member]
Financial assets:
Available-for-sale securities, at fair value (amortized cost of $1,516,057 and $1,508,981, respectively)	0	0
Interest Rate Lock Commitments [Member] | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	134	371
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	313	91
Interest Rate Lock Commitments [Member] | Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	0	0
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value		0
Interest Rate Lock Commitments [Member] | Observable Market Data (Level 2) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	134	371
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	313	91
Interest Rate Lock Commitments [Member] | Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	0	0
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	0	0
Forward delivery commitments | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	246	86
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value		6
Forward delivery commitments | Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	0	0
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value		0
Forward delivery commitments | Observable Market Data (Level 2) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	246	86
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value		6
Forward delivery commitments | Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	0	0
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value		0
Customer loan swaps(1) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	7,843	19,297
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	7,937	19,485
Customer loan swaps(1) | Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	0	0
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	0	0
Customer loan swaps(1) | Observable Market Data (Level 2) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	7,843	19,297
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	7,937	19,485
Customer loan swaps(1) | Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring
Financial assets:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Asset at Fair Value	0	0
Financial liabilities:
Interest Rate Derivative Instruments Not Designated as Hedging Instruments, Liability at Fair Value	0	0
Interest rate contracts(1)
Financial assets:
Fair Value	7,898	5,589
Financial liabilities:
Derivative Liability	6,426	7,872
Interest rate contracts(1) | Fair Value, Measurements, Recurring
Financial assets:
Fair Value	7,898	5,589
Financial liabilities:
Derivative Liability	6,426	7,872
Interest rate contracts(1) | Readily Available Market Prices (Level 1) | Fair Value, Measurements, Recurring
Financial assets:
Fair Value	0	0
Financial liabilities:
Derivative Liability		0
Interest rate contracts(1) | Observable Market Data (Level 2) | Fair Value, Measurements, Recurring
Financial assets:
Fair Value	7,898	5,589
Financial liabilities:
Derivative Liability	6,426	7,872
Interest rate contracts(1) | Company Determined Fair Value (Level 3) | Fair Value, Measurements, Recurring
Financial assets:
Fair Value	0	0
Financial liabilities:
Derivative Liability	$ 0	$ 0