Segment Information - Schedule of Provisions for Contractual Discounts and Estimated Uncompensated Care as a Percentage of Total Segment Billings (Detail) (Air Medical [Member], Sales Revenue, Net [Member])	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Air Medical [Member] | Sales Revenue, Net [Member]
Provisions For Contractual Discounts And Estimated Uncompensated Care [Line Items]
Gross Air Medical segment billings	100.00%	100.00%
Provision for contractual discounts	74.00%	69.00%
Provision for uncompensated care	0.00%	3.00%