Business Segments and Geographic Areas - Schedule of Profit or Loss and Assets of Each of Company's Reportable Segments (Parenthetical) (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment Reporting Information [Line Items]
Interest expense	$ 29,510	$ 29,756	$ 29,533
Reportable Operating Segments [Member] | Air Medical [Member]
Segment Reporting Information [Line Items]
Interest expense		$ 300