Income Taxes - Schedule of Reconciliation of Federal Statutory Rate to Effective Income Tax Rate (Detail)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Abstract]
Federal statutory rate	35.00%	35.00%	35.00%
State income taxes, net of federal tax benefit	2.10%	1.60%	2.30%
Change in liability for uncertain tax positions	(1.00%)	0.20%	0.50%
Tax benefit from settlements of employee equity awards	(3.60%)
Other items, net	(0.20%)	0.40%	(0.60%)
Effective income tax rate on income applicable to HCA Holdings, Inc.	32.30%	37.20%	37.20%
Income attributable to noncontrolling interests from consolidated partnerships	(3.60%)	(5.30%)	(5.40%)
Effective income tax rate on income before income taxes	28.70%	31.90%	31.80%