Acquisitions and Divestitures (Divestitures Narrative) (Details) $ in Millions		3 Months Ended	6 Months Ended	9 Months Ended		12 Months Ended
	May 01, 2017 USD ($) item	Mar. 31, 2016 USD ($)	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2017 USD ($) item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 item
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of Hospitals Sold | item						30
Proceeds from Divestiture of Businesses, Net of Cash Divested						$ 1,692	$ 143	$ 155
Impairment of goodwill			$ 1,400		$ 1,395	1,419	1,395
Impairment and (gain) loss on sale of businesses, net						2,123	1,919	68
Impairment of hospitals in discontinued operations						6	8	5
Goodwill, Written off Related to Disposal of Assets Held-for-Sale						$ 357	365
Gain on sale								(4)
Williamson Memorial Hospital [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Number of licensed beds | item									76
AllianceHealth Pryor [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Date						May 01, 2017
Number of licensed beds | item	52
Proceeds from Divestiture of Businesses, Net of Cash Divested	$ 1
McNairy Regional Hospital [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment and (gain) loss on sale of businesses, net		$ 7		$ 0
Hospitals in Period [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Impairment and (gain) loss on sale of businesses, net						$ 368	$ 463	$ 0
Almost Family, Inc. [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal Date						Dec. 31, 2016
Percentage of ownership interest sold							80.00%
Proceeds from Divestiture of Businesses, Net of Cash Divested							$ 128
Gain on sale							$ 91