Acquisitions and Divestitures (Acquisitions Narrative) (Details) $ in Millions			3 Months Ended		9 Months Ended
	Apr. 01, 2016 USD ($) item	Mar. 01, 2016 USD ($) item	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Business Acquisition [Line Items]
Business Acquisition, Purchase Price Allocation, Goodwill			$ 6,901		$ 6,901		$ 8,965
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		$ 12
Business Acquisition, Percentage of Voting Interests Acquired	80.00%
Business Combination, Assumed Noncontrolling Interest, Fair Value	$ 3
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			46		$ 46
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			1	$ 2	4	$ 6
Physician Practices Clinics and Other Ancillary Businesses [Member]
Business Acquisition [Line Items]
Business Combination, Assumed Noncontrolling Interest, Fair Value			6		6
Business Acquisition, Cost of Acquired Entity, Cash Paid					14
Business Acquisition, Purchase Price Allocation, Property, Plant and Equipment			7		7
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Intangible Assets, Other than Goodwill			$ 13		$ 13