Asset Disposals and Impairments - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended			9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Oil And Gas [Member]	Sep. 30, 2013 Light Aircraft [Member] Oil And Gas [Member] Aircraft	Jun. 30, 2013 Heavy Transport Aircraft [Member] Oil And Gas [Member] Aircraft	Sep. 30, 2013 Medium Aircraft [Member] Air Medical [Member] Aircraft
Assets Held For Sale And Impairments [Line Items]
Carrying value of aircraft	$ 782,247,000		$ 782,247,000		$ 749,501,000		$ 1,200,000	$ 20,600,000	$ 800,000
Sale value of aircraft							2,600,000	37,000,000
Gain on sale of aircraft	1,399,000	(701,000)	16,075,000	(11,000)			1,400,000	16,400,000
Number of aircraft sold							1	2
Loss on sale of Assets						1,700,000
Current market value for aircraft									400,000
Impairment loss			$ 421,000						$ 400,000
Number of aircraft written down									2