MERGER WITH PLUM CREEK Additional Information (Details) - Plum Creek [Member] $ in Millions	3 Months Ended	12 Months Ended
Mar. 31, 2016 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)	Feb. 19, 2016
Business Acquisition [Line Items]
Exchange ratio per the merger agreement				1.60
Merger-related costs	$ 110	$ 0	$ 14
Non-recurring merger-related costs	$ 131	$ 0

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=73531572&loc=d3e1043-128460

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- Definition

Costs incurred to effect a business combination which have been expensed during the period. Such costs could include business integration costs, systems integration and conversion costs, and severance and other employee-related costs.

+ References

No definition available.

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- Definition

The conversion ratio ratio for equity shares issued or issuable to acquire entity.

+ References

No definition available.

+ Details

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- Details

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