Acquisitions and Dispositions - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) Hospital	Dec. 31, 2018 USD ($) Hospital	Dec. 31, 2017 USD ($) Hospital
Business Acquisition [Line Items]
Number of hospitals purchased | Hospital	7	2	8
Proceeds from sale of business	$ 61	$ 808	$ 25
Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Proceeds from sales of real estate	36	50	8
Pretax gain (loss) after tax	19	75	5
Proceeds from sale of business	14	59	25
Discontinued Operations, Disposed of by Sale [Member] | Oklahoma [Member]
Business Acquisition [Line Items]
Proceeds from sales of real estate	1	353
Pretax gain (loss) after tax	1	265
Proceeds from sale of business	$ 25	$ 758
Number of hospitals sold | Hospital	1	2
Hospitals [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 1,384	$ 792	1,000
Nonhospital Health Care [Member]
Business Acquisition [Line Items]
Aggregate purchase price	298	461	212
Other [Member]
Business Acquisition [Line Items]
Goodwill	$ 332	$ 636	$ 693