Acquisitions and Dispositions - Additional Information (Detail) $ in Thousands	12 Months Ended
	Dec. 31, 2018 USD ($) Hospital	Dec. 31, 2017 USD ($) Hospital	Dec. 31, 2016 USD ($) Hospital
Business Acquisition [Line Items]
Number of hospitals purchased | Hospital	2	8	3
Proceeds from sale of business	$ 808,000	$ 25,000	$ 26,000
Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	50,000	8,000	23,000
Pretax gain (loss) after tax	75,000	5,000	19,000
Proceeds from sale of business	59,000	25,000	26,000
Discontinued Operations, Disposed of by Sale [Member] | Oklahoma [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	353,000
Pretax gain (loss) after tax	265,000
Proceeds from sale of business	$ 758,000
Number of hospitals sold | Hospital	2,000,000
Hospitals [Member]
Business Acquisition [Line Items]
Aggregate purchase price	$ 792,000	1,000,000	343,000
Nonhospital Health Care [Member]
Business Acquisition [Line Items]
Aggregate purchase price	461,000	212,000	233,000
Other [Member]
Business Acquisition [Line Items]
Fair value of identifiable net assets of acquired entities	$ 636,000	$ 693,000	$ 41,000