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ACQUISITIONS AND DIVESTITURES - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		6 Months Ended
	Jun. 01, 2015	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Gain on sale of business		$ 0	$ 267	$ 0	$ 267
Concentra Inc.
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Selling price in cash	$ 1,055
Disposal transaction costs	22
Gain on sale of business	$ 270		267
Revenues			166		411
Pretax earnings			$ 8		$ 15