Segment Information - Schedule of Provisions for Contractual Discounts and Estimated Uncompensated Care as a Percentage of Gross Segment Billings (Detail)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Segment Reporting [Abstract]
Provision for contractual discounts	73.00%	62.00%	71.00%	60.00%
Provision for uncompensated care	0.00%	8.00%	3.00%	9.00%