Acquisitions and Dispositions - Additional Information (Detail) $ in Millions	6 Months Ended
Jun. 30, 2018 USD ($) Hospital	Jun. 30, 2017 USD ($) Hospital
Business Acquisition [Line Items]
Number of hospitals purchased \| Hospital		3
Proceeds from sale of business	$ 799	$ 14
Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	42	3
Proceeds from sale of business	41	14
Discontinued Operations, Disposed of by Sale [Member] \| Oklahoma [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	372
Proceeds from sale of business	$ 758
Number of hospitals sold \| Hospital	2
Hospitals [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 360	189
Nonhospital Health Care [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 178	$ 106

Number of hospitals acquired.

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Number of hospitals sold.

+ References

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Amount before tax of gain (loss) not previously recognized resulting from the disposal of a discontinued operation.

+ References

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The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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The cash inflow associated with the amount received from the sale of a portion of the company's business, for example a segment, division, branch or other business, during the period.

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