Basis of Presentation and Significant Accounting Policies - Additional Information (Detail) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015 USD ($) Hospital State Surgery_Center	Jun. 30, 2014 USD ($) $ / shares	Jun. 30, 2015 USD ($) $ / shares Hospital State Surgery_Center	Jun. 30, 2014 USD ($)
Accounting Policies [Abstract]
Number of owned and operated hospitals | Hospital	168		168
Number of freestanding surgery centers | Surgery_Center	112		112
Number of facilities locations | State	20		20
General and administrative expense	$ 84	$ 67	$ 158	$ 135
Adjustments to Medicare revenues		$ 142	$ 142
Adjustment to increase Medicaid revenues in diluted per share | $ / shares		$ 0.20	$ 0.20