Investments (Details) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended	0 Months Ended			1 Months Ended	9 Months Ended	12 Months Ended		33 Months Ended			1 Months Ended	6 Months Ended	9 Months Ended		1 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Dec. 31, 2012	Sep. 18, 2013 WOLF item	Sep. 30, 2013 Term notes WOLF	Sep. 18, 2013 Term notes WOLF item	Jun. 30, 2011 WMES item	Sep. 30, 2013 WMES item	Dec. 31, 2012 WMES	Dec. 31, 2011 WMES	Sep. 30, 2013 WMES item	May 25, 2011 WMES	Sep. 30, 2013 WMES JA Mitsui Leasing, Ltd	Dec. 31, 2005 WOLF item	Jun. 30, 2013 WOLF	Sep. 30, 2013 WOLF item	Dec. 31, 2012 WOLF	May 31, 2013 WOLF Term notes item	May 31, 2013 WOLF Amended term notes item	Sep. 30, 2013 WOLF Amended term notes	Sep. 30, 2013 WOLF Minimum	Sep. 30, 2013 WOLF Maximum
Investments
Previously held interest (as a percent)										50.00%			50.00%					50.00%
Initial capital contribution														$ 8,000,000
Additional capital contributions										6,100,000	5,600,000	1,000,000
Number of engines transfer to joint venture									7
Number of engines purchased													16
Number of engines in lease portfolio										23								8
Capital contributions to date										20,700,000			20,700,000
Proportionate gain on sale of engines to joint venture interest which is off-set against investments										3,600,000
Net investment after deducting partial offset										17,100,000			17,100,000
Gain on sale of engines									7,200,000
Credit facility established by equity method investee										8,000,000			8,000,000		180,000,000
Reference rate, description			one-month LIBOR		one-month LIBOR		one-month LIBOR											one-month LIBOR				one-month LIBOR
Margin (as a percent)							4.00%															4.00%	1.00%	2.50%
Maturity term										7 years
Maintenance reserve revenue	8,891,000	10,653,000	29,908,000	28,668,000													9,000,000
Investment in joint venture	18,072,000		18,072,000		21,831,000					18,072,000	11,766,000		18,072,000						10,065,000
Number of Airbus A340-313 aircraft purchased																2
Purchase price of aircraft																96,000,000
Number of term notes held								2								4
Number of financial institutions associated with funding of term notes																1
Loan for purchase of aircraft								36,000,000								76,800,000					36,000,000
Number of term notes paid off																				2
Number of term notes amended																					2
Acquisition of the remaining outstanding shares (as a percent)						50.00%
Purchase price consideration						1,000,000
Discount from JV partner's equity interest						12,700,000
Number of aircraft engines acquired						8
Number of aircraft airframes acquired						2
Fair value of the net assets acquired						12,600,000
Amount of equipment acquired						27,000,000
Amount of cash and receivables acquired						1,600,000
Amount of debt and other liabilities						$ 16,000,000
Controlling interest assumed (as a percent)						100.00%