Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) $ in Millions		1 Months Ended	3 Months Ended		6 Months Ended		12 Months Ended
	Oct. 31, 2017	Nov. 30, 2017	Jun. 30, 2018 USD ($) State Hospital Surgery_Center	Jun. 30, 2017 USD ($)	Jun. 30, 2018 USD ($) State Hospital Surgery_Center	Jun. 30, 2017 USD ($)	Dec. 31, 2017 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Number of owned and operated hospitals | Hospital			178		178
Number of freestanding surgery centers | Surgery_Center			122		122
Number of facilities locations | State			20		20
General and administrative expense			$ 83	$ 82	$ 164	$ 164
Estimated implicit price concessions recorded as reductions to revenues and accounts receivable					$ 5,736		$ 5,488
Percentage of sum of revenues and uncompensated care			36.00%	34.80%	35.70%	34.10%
Charity care amount			$ 1,977	$ 1,173	$ 3,856	$ 2,259
Estimated costs of charity care			$ 249	$ 152	$ 482	$ 291
Inpatient Services [Member]
Summary Of Significant Accounting Policies [Line Items]
Performance obligations for inpatient/ outpatient services satisfied period			5 days		5 days
Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of income of federal poverty level eligible for charity care	200.00%	400.00%
Maximum [Member] | Outpatient Services [Member]
Summary Of Significant Accounting Policies [Line Items]
Performance obligations for inpatient/ outpatient services satisfied period			1 day		1 day
Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage of income of federal poverty level eligible for charity care		200.00%