LOANS AND ALLOWANCE FOR LOAN LOSSES - Nonperforming loans - (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Loans past due 90 days or more still on accrual	$ 265	$ 2,135
Troubled debt restructurings (accruing)	3,845	6,474
Non-accrual loans	15,895	15,808
Total	3,063,463	2,651,673
Nonperforming loans
Recorded investment in nonaccrual and loans past due over 90 days still on accrual and aging of recorded investment in past due
Loans past due 90 days or more still on accrual	265	2,135
Troubled debt restructurings (accruing)	2,403	3,270
Non-accrual loans	15,895	15,808
Total	$ 18,563	$ 21,213

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

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Recorded investment in financing receivables that are 90 days or more past due and still accruing.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Recorded Investment
-URI http://asc.fasb.org/extlink&oid=65880944

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=66008989&loc=d3e5111-111524

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Recorded investment in financing receivables that are on nonaccrual status as of the balance sheet date.

+ References

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No definition available.

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Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=65884687&loc=d3e4428-111522

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