PENSION AND POSTRETIREMENT WELFARE PLANS - Weighted-Average Assumptions (Details) - Pension Plan - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Weighted average assumptions used to determine the benefit obligation
Discount rate (as a percent)	4.25%	4.00%	4.75%
Rate of compensation increases (as a percent)	2.00%	2.00%	2.00%
Weighted average assumptions used to determine net periodic expense
Discount rate (as a percent)	4.00%	4.75%	4.00%
Expected long-term rate of return on plan assets (as a percent)	6.50%	7.00%	7.00%
Rate of compensation increases (as a percent)	2.00%	2.00%	5.00%
Expected contributions
Expected contributions during next fiscal year	$ 0
Pension plans' actual percentage of plan assets and the target percentage of plan assets
Actual percentage of plan assets	100.00%	100.00%
Total (as a percent)	100.00%
Cash equivalents
Pension plans' actual percentage of plan assets and the target percentage of plan assets
Actual percentage of plan assets	7.00%	5.00%
Equity securities
Pension plans' actual percentage of plan assets and the target percentage of plan assets
Actual percentage of plan assets	62.00%	64.00%
Minimum (as a percent)	55.00%
Maximum (as a percent)	75.00%
Fixed income securities
Pension plans' actual percentage of plan assets and the target percentage of plan assets
Actual percentage of plan assets	31.00%	31.00%
Minimum (as a percent)	25.00%
Maximum (as a percent)	45.00%
Cash
Pension plans' actual percentage of plan assets and the target percentage of plan assets
Minimum (as a percent)	0.00%
Maximum (as a percent)	20.00%

The interest rate used to adjust for the time value of money for the plan.

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- Definition

Expected rate of compensation increases (for pay-related plans).

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The interest rate used to adjust for the time value of money.

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Expected Long-Term Rate of Return on Plan Assets
-URI http://asc.fasb.org/extlink&oid=6512046

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (k)(3)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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Expected rate of compensation increases (for pay-related plans).

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- Definition

Target allocation of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
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-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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Target allocation maximum percentage of investments of this type to total plan assets presented on a weighted average basis.

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Target allocation minimum percentage of investments of this type to total plan assets presented on a weighted average basis.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920

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- Definition

Percentage of fair value of investments (categorized by debt securities, equity securities, real estate and other plan assets) to the fair value of plan assets held.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 5
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2446-114920

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-Publisher FASB
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-SubTopic 20
-Section 50
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920

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- Definition

Amount of employer's best estimate of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position.

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