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FAIR VALUE - Financial Assets and Liabilities Accounted for at Fair Value On a Recurring Basis (Details) - USD ($) | Dec. 31, 2021 | Dec. 31, 2020
--- | --- | ---
Available-for-sale investment securities |  |
Available-for-sale investment securities | $ 4,934,210,000 |
Equity securities | 463,000 | $ 445,000
U.S. Treasury and Agency Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 3,998,564,000 | 2,501,382,000
Obligations of State and Political Subdivisions |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 430,289,000 | 475,660,000
Government Agency Mortgage-Backed Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 477,056,000 | 522,638,000
Corporate debt securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 7,962,000 | 4,635,000
Government Agency Collateralized Mortgage Obligations |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 20,339,000 | 43,577,000
Significant Unobservable Inputs, Level 3 | Commitments to Originate Real Estate Loans for Sale |  |
Available-for-sale investment securities |  |
Derivative asset | 51,000 | 14,000
Recurring |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 4,934,210,000 | 3,547,892,000
Equity securities | 463,000 | 445,000
Mortgage loans held for sale |  | 1,622,000
Total | 4,935,049,000 | 3,550,473,000
Recurring | Interest Rate Swap Agreements |  |
Available-for-sale investment securities |  |
Derivative asset | 296,000 | 1,572,000
Derivative liability | (3,000) | (1,074,000)
Recurring | ForwardContractsMember |  |
Available-for-sale investment securities |  |
Derivative asset |  | 2,000
Derivative liability | 32,000 |
Recurring | Commitments to Originate Real Estate Loans for Sale |  |
Available-for-sale investment securities |  |
Derivative asset | 51,000 | 14,000
Recurring | U.S. Treasury and Agency Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 3,998,564,000 | 2,501,382,000
Recurring | Obligations of State and Political Subdivisions |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 430,289,000 | 475,660,000
Recurring | Government Agency Mortgage-Backed Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 477,056,000 | 522,638,000
Recurring | Corporate debt securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 7,962,000 | 4,635,000
Recurring | Government Agency Collateralized Mortgage Obligations |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 20,339,000 | 43,577,000
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 3,900,924,000 | 2,359,912,000
Equity securities | 463,000 | 445,000
Mortgage loans held for sale |  | 0
Total | 3,901,387,000 | 2,360,357,000
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | Interest Rate Swap Agreements |  |
Available-for-sale investment securities |  |
Derivative asset | 0 | 0
Derivative liability | 0 | 0
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | ForwardContractsMember |  |
Available-for-sale investment securities |  |
Derivative asset |  | 0
Derivative liability | 0 |
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | Commitments to Originate Real Estate Loans for Sale |  |
Available-for-sale investment securities |  |
Derivative asset | 0 | 0
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | U.S. Treasury and Agency Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 3,900,924,000 | 2,359,912,000
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | Obligations of State and Political Subdivisions |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | Government Agency Mortgage-Backed Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | Corporate debt securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Quoted Prices in Active Markets For Identical Assets, Level 1 | Government Agency Collateralized Mortgage Obligations |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Significant Observable Inputs, Level 2 |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 1,033,286,000 | 1,187,980,000
Equity securities | 0 | 0
Mortgage loans held for sale | 0 | 1,622,000
Total | 1,033,611,000 | 1,190,102,000
Recurring | Significant Observable Inputs, Level 2 | Interest Rate Swap Agreements |  |
Available-for-sale investment securities |  |
Derivative asset | 296,000 | 1,572,000
Derivative liability | (3,000) | (1,074,000)
Recurring | Significant Observable Inputs, Level 2 | ForwardContractsMember |  |
Available-for-sale investment securities |  |
Derivative asset |  | 2,000
Derivative liability | 32,000 |
Recurring | Significant Observable Inputs, Level 2 | Commitments to Originate Real Estate Loans for Sale |  |
Available-for-sale investment securities |  |
Derivative asset | 0 | 0
Recurring | Significant Observable Inputs, Level 2 | U.S. Treasury and Agency Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 97,640,000 | 141,470,000
Recurring | Significant Observable Inputs, Level 2 | Obligations of State and Political Subdivisions |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 430,289,000 | 475,660,000
Recurring | Significant Observable Inputs, Level 2 | Government Agency Mortgage-Backed Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 477,056,000 | 522,638,000
Recurring | Significant Observable Inputs, Level 2 | Corporate debt securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 7,962,000 | 4,635,000
Recurring | Significant Observable Inputs, Level 2 | Government Agency Collateralized Mortgage Obligations |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 20,339,000 | 43,577,000
Recurring | Significant Unobservable Inputs, Level 3 |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Equity securities | 0 | 0
Mortgage loans held for sale |  | 0
Total | 51,000 | 14,000
Recurring | Significant Unobservable Inputs, Level 3 | Interest Rate Swap Agreements |  |
Available-for-sale investment securities |  |
Derivative asset | 0 | 0
Derivative liability | 0 | 0
Recurring | Significant Unobservable Inputs, Level 3 | ForwardContractsMember |  |
Available-for-sale investment securities |  |
Derivative asset |  | 0
Derivative liability | 0 |
Recurring | Significant Unobservable Inputs, Level 3 | Commitments to Originate Real Estate Loans for Sale |  |
Available-for-sale investment securities |  |
Derivative asset | 51,000 | 14,000
Recurring | Significant Unobservable Inputs, Level 3 | U.S. Treasury and Agency Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Significant Unobservable Inputs, Level 3 | Obligations of State and Political Subdivisions |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Significant Unobservable Inputs, Level 3 | Government Agency Mortgage-Backed Securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Significant Unobservable Inputs, Level 3 | Corporate debt securities |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | 0 | 0
Recurring | Significant Unobservable Inputs, Level 3 | Government Agency Collateralized Mortgage Obligations |  |
Available-for-sale investment securities |  |
Available-for-sale investment securities | $ 0 | $ 0

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