Contingencies and Legal Claim Costs - Additional Information (Detail) - USD ($) $ in Millions				1 Months Ended	3 Months Ended				9 Months Ended
	Dec. 09, 2015	Feb. 09, 2015	Jan. 24, 2013	Apr. 25, 2014	Sep. 30, 2016	Sep. 30, 2015	Mar. 31, 2014	Dec. 31, 2012	Sep. 30, 2016	Sep. 30, 2015	Oct. 31, 2009
Loss Contingencies [Line Items]
Capital commitment in connection with purchase of hospitals											$ 450
Additional shortfall related to capital expenditures				$ 78
Legal claim costs	$ 434				$ 11	$ 77	$ 78	$ 175	$ 33	$ 77
Period of agreed capital commitments									5 years
Number of year under court-supervisor accounting for expenditures following the purchase									10 years
Percentage of legal claim costs	9.00%
Dispute settlement amount		$ 15
Accrued Liability					$ 468				$ 468
Health Care Foundation of Greater Kansas City [Member] | Pending Litigation [Member]
Loss Contingencies [Line Items]
Judgment award by the court			$ 162
Plaintiff attorneys fees award									$ 12
Percentage of legal claim costs							9.00%	9.00%