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EMPLOYEE BENEFIT PLANS - Weighted average asset allocation by asset category along with target allocation (Details) - Retirement Income Plan	Dec. 31, 2020	Dec. 31, 2019
EMPLOYEE BENEFIT PLANS
Percentage of Plan Assets	100.00%	100.00%
Target Allocation for 2021	100.00%
Cash and Cash Equivalents
EMPLOYEE BENEFIT PLANS
Percentage of Plan Assets	2.00%	1.30%
Fixed Income Securities
EMPLOYEE BENEFIT PLANS
Percentage of Plan Assets	98.00%	91.70%
Investments measured at net asset value
EMPLOYEE BENEFIT PLANS
Percentage of Plan Assets	0.00%	7.00%
Minimum | Cash and Cash Equivalents
EMPLOYEE BENEFIT PLANS
Target Allocation for 2021	0.00%
Minimum | Fixed Income Securities
EMPLOYEE BENEFIT PLANS
Target Allocation for 2021	15.00%
Maximum | Cash and Cash Equivalents
EMPLOYEE BENEFIT PLANS
Target Allocation for 2021	5.00%
Maximum | Fixed Income Securities
EMPLOYEE BENEFIT PLANS
Target Allocation for 2021	100.00%

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- Definition

Percentage of target investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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- Definition

Percentage of actual investment allocation to total plan assets. Includes, but is not limited to, percentage on weighted-average basis if more than one plan.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=118255775&loc=d3e1928-114920

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