DEPOSITS (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Mar. 31, 2021
Time Deposits [Line Items]
Money market deposit accounts	$ 847,430	$ 918,940
Time deposits	172,682	157,072
Negotiable order of withdrawal accounts	113,052	130,540
Savings accounts	5,289	7,885
Total interest bearing deposits	1,138,453	1,214,437
Aggregate time deposits of $250,000 or greater	73,401	$ 72,490
Overdrafts balances classified As loans	100
Simmons Bank
Time Deposits [Line Items]
Deposits acquired via acquisitions	$ 63,100

Amount of deposits assumed in business combination.

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- Definition

Amount of overdraft balances classified as loans.

+ References

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- Definition

Amount of time deposit liabilities of $250,000 or more, including certificates of deposit.

+ References

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- Definition

Amount of deposits in accounts that offer many of the same services as checking accounts although transactions may be somewhat more limited, share some of the characteristics of a money market fund and are insured by the Federal government, also known as money market accounts.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

Amount of deposits in interest-bearing transaction accounts at banks or savings and loans, that are restricted in regard to ownership and can usually only be held by individuals, nonprofit entities and governments. Negotiable order of withdrawal accounts differ from money market demand accounts as they typically have higher reserve requirements and no limit on the number of checks that can be written.

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- Definition

Amount of interest bearing deposits with no stated maturity, which may include passbook and statement savings accounts and money-market deposit accounts (MMDAs).

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- Definition

The aggregate of all domestic and foreign interest-bearing deposit liabilities.

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- Definition

Amount of time deposit liabilities, including certificates of deposit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 405
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=116652737&loc=d3e64164-112818

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.12)
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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