Acquisitions and Dispositions - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2016 USD ($) Hospital	Dec. 31, 2015 USD ($) Hospital	Dec. 31, 2014 USD ($) Hospital
Business Acquisition [Line Items]
Number of hospitals acquired | Hospital	3	1	3
Proceeds from sale of business	$ 26	$ 73	$ 51
Hospitals [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	343	15	161
Nonhospital Health Care [Member]
Business Acquisition [Line Items]
Cash paid for acquisition	233	336	605
Other [Member]
Business Acquisition [Line Items]
Fair value of identifiable net assets of acquired entities	41	323	542
Real Estate and Other Investments [Member]
Business Acquisition [Line Items]
Pretax gain (loss) on sales of business	23	(5)	29
Proceeds from sale of business	$ 26	$ 73	$ 51