Basis of Presentation and Significant Accounting Policies (Narrative) (Details)	3 Months Ended									12 Months Ended						24 Months Ended
	Dec. 31, 2019 USD ($) state item	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2019 USD ($) segment state item		Dec. 31, 2018 USD ($)		Dec. 31, 2017 USD ($) item	Dec. 31, 2016	Dec. 31, 2019 USD ($) state item	Jan. 01, 2019 USD ($)	Jan. 01, 2018 USD ($)
Business Description [Abstract]
Number of hospitals owned and leased by the Company | item	102									102						102
Number of licensed beds | item	16,240									16,240						16,240
Number of stand alone rehabilitation or psychiatric hospitals | item	2									2						2
Number of states in which entity operates | state	18									18						18
Cost of Revenue, Policy [Abstract]
Corporate office costs										$ 184,000,000		$ 181,000,000		$ 189,000,000
Stock-based compensation expense										10,000,000		13,000,000		24,000,000
Marketable Securities, Policy [Abstract]
Net change in fair value of available-for-sale debt securities, net of tax										4,000,000		(2,000,000)		8,000,000
Property and Equipment, Policy [Abstract]
Construction in Progress, Gross	$ 219,000,000				$ 219,000,000					219,000,000		219,000,000				$ 219,000,000
Interest Costs Capitalized										20,000,000		15,000,000		11,000,000
Purchases of property and equipment accrued in accounts payable										93,000,000		115,000,000
Goodwill, Policy [Abstract]
Impairment of goodwill										0		0		1,419,000,000
Other Assets, Policy [Abstract]
Cash paid to increase investments in certain equity method investments										28,000,000
Third-Party Reimbursement [Abstract]
Amounts due to third party payors	83,000,000				144,000,000					83,000,000		144,000,000				83,000,000
Amounts due from third party payors	137,000,000				155,000,000					137,000,000		155,000,000				137,000,000
Net Operating Revenues, Policy [Abstract]
Value of charity care services at the Company's standard charges included in contractual allowances										540,000,000		491,000,000		482,000,000
Estimated cost incurred by Company to provide charity care services										66,000,000		62,000,000		$ 62,000,000
Allowance for Doubtful Accounts, Policy [Abstract]
Number of Hospitals Sold | item														30
Electronic Health Records Reimbursement, Policy [Abstract]
Electronic health records incentive reimbursement under HITECH										1,000,000		4,000,000		$ 28,000,000
Electronic Health Records Incentive Reimbursement, Cash Received										1,000,000		4,000,000		41,000,000
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances	2,258,000,000				2,352,000,000					2,258,000,000		2,352,000,000				2,258,000,000
Decrease in net operating revenues	3,286,000,000	$ 3,246,000,000	$ 3,302,000,000	$ 3,376,000,000	3,453,000,000	$ 3,451,000,000	$ 3,562,000,000	$ 3,689,000,000		13,210,000,000	[1]	14,155,000,000	[1]	15,353,000,000
Accounting for the Impairment or Disposal of Long-Lived Assets
Goodwill allocated to hospital disposal group held for sale	235,000,000				186,000,000					235,000,000		186,000,000				235,000,000
Impairment and loss on sale of businesses, net										$ 138,000,000		668,000,000		2,123,000,000
Segment Reporting, Policy [Abstract]
Number of reportable segments | segment										1
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset	607,000,000									$ 607,000,000						607,000,000
Operating lease liability	623,000,000									623,000,000						623,000,000
Adoption of ASC 606 [Member]
Net Operating Revenues, Policy [Abstract]
Provision for contractual allowance included in net operating revenues														197,000,000
Allowance for doubtful patient accounts									$ 394,000,000					394,000,000
Concentration of Credit Risk, Policy [Abstract]
Decrease in net operating revenues										13,210,000,000		14,155,000,000
ASU 2016-02 [Member]
New Accounting Pronouncements, Policy [Abstract]
Operating lease right-of-use asset																	$ 673,000,000
Operating lease liability																	$ 673,000,000
Difference between Revenue Guidance in Effect before and after Topic 606 [Member]
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances																		$ 3,900,000,000
Medicare [Member]
Concentration of Credit Risk, Policy [Abstract]
Accounts receivable, net of contractual allowances	268,000,000				283,000,000					268,000,000		283,000,000				$ 268,000,000
Accounts receivable net of contractual allowances, percent																5.00%
Medicare [Member] | Adoption of ASC 606 [Member]
Concentration of Credit Risk, Policy [Abstract]
Decrease in net operating revenues										3,331,000,000		3,730,000,000
Electronic Health Records Incentive Reimbursements [Member]
Electronic Health Records Reimbursement, Policy [Abstract]
Deferred Revenue	0				0				0	0		0		$ 0		$ 0
Maximum [Member]
Physician Income Guarantees, Policy [Abstract]
Finite-Lived Intangible Assets, Net	1,000,000				1,000,000					$ 1,000,000		1,000,000				1,000,000
Capitalized Internal Use Software, Significant System Conversions [Member] | Minimum [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life										8 years
Capitalized Internal Use Software, Significant System Conversions [Member] | Maximum [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life										10 years
Capitalized Internal Use Software, Except Significant System Conversions [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life										3 years
Finite-Lived Intangible Assets, Except Capitalized Internal-Use Software [Member]
Other Assets, Policy [Abstract]
Finite-Lived Intangible Assets, Weighted-Average Useful Life										1 year
Physician recruitment contracts [Member]
Physician Income Guarantees, Policy [Abstract]
Physicians recruitment agreement period										1 year
Term of Physician Recruitment Contract										3 years
Finite-Lived Intangible Assets, Net	20,000,000				24,000,000					$ 20,000,000		$ 24,000,000				20,000,000
Land Improvements [Member] | Minimum [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life										3 years
Land Improvements [Member] | Maximum [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life										20 years
Building and Building Improvements [Member] | Minimum [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life										5 years
Building and Building Improvements [Member] | Maximum [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life										40 years
Equipment and Fixtures [Member] | Minimum [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life										3 years
Equipment and Fixtures [Member] | Maximum [Member]
Property and Equipment, Policy [Abstract]
Property, Plant and Equipment, Useful Life										18 years
Certain Facility [Member]
Property and Equipment, Policy [Abstract]
Non-cash investing activity through capital leases										$ 6,000,000
Sales Revenue, Net [Member] | Adoption of ASC 606 [Member]
Concentration of Credit Risk, Policy [Abstract]
Decrease in net operating revenues									$ (591,000,000)
Geographic Concentration Risk [Member] | Florida [Member] | Sales Revenue, Net [Member]
Business Description [Abstract]
Concentration Risk, Percentage										14.30%		14.30%		14.00%
Geographic Concentration Risk [Member] | Texas [Member] | Sales Revenue, Net [Member]
Business Description [Abstract]
Concentration Risk, Percentage										12.20%		11.70%		10.90%
Geographic Concentration Risk [Member] | Indiana [Member] | Sales Revenue, Net [Member]
Business Description [Abstract]
Concentration Risk, Percentage										13.70%		12.50%		11.60%
Certain Hospitals [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment of long-lived assets held for sale										$ 138,000,000		$ 668,000,000
Goodwill allocated to hospital disposal group held for sale	$ 167,000,000				$ 186,000,000					167,000,000		186,000,000				$ 167,000,000
Certain Hospitals [Member] | Hospitals Sold or Deemed Held for Sale [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment of long-lived assets held for sale										92,000,000		423,000,000
Certain Hospitals [Member] | Write-Off Promissory Note Received as Consideration For the Sale of Hospitals [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment of long-lived assets held for sale												29,000,000
Certain Hospitals [Member] | Adjustment for Carrying Value of Other Long-Lived Assets at Underperforming Hospitals [Member]
Accounting for the Impairment or Disposal of Long-Lived Assets
Impairment of long-lived assets held for sale										$ 46,000,000		$ 216,000,000
Home Care [Member]
Segment Reporting, Policy [Abstract]
Percentage of Ownership Interest Sold															80.00%

[1] Total quarterly amounts may not add due to rounding.