Acquisitions and Divestitures (Acquisitions Narrative) (Details) $ in Millions			12 Months Ended
	Apr. 01, 2016 USD ($) item	Mar. 01, 2016 USD ($) item	Dec. 31, 2017 USD ($) state item	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Business Acquisition, Purchase Price Allocation, Goodwill			$ 4,723	$ 6,521	$ 8,965
Number of States in which Entity Operates | state			19
Number of Hospitals Owned and Leased by the Company | item			125
Business Combination, Pro Forma Information, Revenue of Acquiree since Acquisition Date, Actual				214
Physicians' Specialty Hospital [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition			Apr. 01, 2016
Business Acquisition, Number of Licensed Hospital or Facility Beds | item	20
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities	$ 2
Business Acquisition, Cost of Acquired Entity, Purchase Price	$ 14
Business Acquisition, Purchase Price Allocation, Goodwill				12
Business Acquisition, Percentage of Voting Interests Acquired	80.00%
Business Combination, Assumed Noncontrolling Interest, Fair Value	$ 2
Business Acquisition, Cost of Acquired Entity, Cash Paid	$ 12
Indiana University Health [Member]
Business Acquisition [Line Items]
Business Acquisition, Effective Date of Acquisition			Mar. 01, 2016
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities		$ 8
Business Acquisition, Cost of Acquired Entity, Purchase Price		$ 104
Business Acquisition, Purchase Price Allocation, Goodwill				45
Business Acquisition, Percentage of Voting Interests Acquired		80.00%
Business Combination, Assumed Noncontrolling Interest, Fair Value		$ 25
Business Acquisition, Cost of Acquired Entity, Cash Paid		$ 96
IU Health La Porte Hospital [Member]
Business Acquisition [Line Items]
Business Acquisition, Number of Licensed Hospital or Facility Beds | item		227
IU Health Starke Hospital [Member]
Business Acquisition [Line Items]
Business Acquisition, Number of Licensed Hospital or Facility Beds | item		50
Health Management Associates, Inc. [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs					1
Excluding Health Management Associates Inc [Member]
Business Acquisition [Line Items]
Business Combination, Acquisition Related Costs			$ 2	5	8
Physician Practices Clinics and Other Ancillary Businesses [Member]
Business Acquisition [Line Items]
Business Acquisition, Cost of Acquired Entity, Purchase Price			6	16	51
Business Combination, Assumed Noncontrolling Interest, Fair Value			0	6	7
Business Acquisition, Purchase Price Allocation, Property, Plant and Equipment			2	8	19
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 4	$ 14	$ 39