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EMPLOYEE RETIREMENT PLANS - Qualified Defined-benefit Pension Plan Weighted Average Asset Allocation (Details) - USD ($) $ in Millions | Dec. 31, 2017 | Dec. 31, 2016
--- | --- | ---
Plan Assets |  |
Unfunded commitments | $ 2 |
Qualified |  |
Plan Assets |  |
Weighted average asset allocation (as a percent) | 100.00% | 100.00%
Qualified | Equity securities |  |
Plan Assets |  |
Weighted average asset allocation (as a percent) | 55.00% | 49.00%
Qualified | Debt securities |  |
Plan Assets |  |
Weighted average asset allocation (as a percent) | 28.00% | 32.00%
Qualified | Other |  |
Plan Assets |  |
Weighted average asset allocation (as a percent) | 17.00% | 19.00%

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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=65897934&loc=d3e2446-114920 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (d)(1) -URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920 + Details
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