Investments (Details) (USD $)	1 Months Ended	6 Months Ended	12 Months Ended			39 Months Ended
	Jun. 30, 2011 Willis Mitsui And Company Engine Support Limited [Member] engine	Jun. 30, 2014 Willis Mitsui And Company Engine Support Limited [Member] item	Dec. 31, 2013 Willis Mitsui And Company Engine Support Limited [Member]	Dec. 31, 2012 Willis Mitsui And Company Engine Support Limited [Member]	Dec. 31, 2011 Willis Mitsui And Company Engine Support Limited [Member]	Jun. 30, 2014 Willis Mitsui And Company Engine Support Limited [Member] engine	May 25, 2011 Willis Mitsui And Company Engine Support Limited [Member]	Jun. 03, 2014 Casc Willis Engine Lease Company Limited [Member]
Investments
Ownership percentage		50.00%				50.00%		50.00%
Initial capital contribution							$ 8,000,000	$ 15,000,000
Capital contributions		0	11,200,000	5,600,000	1,000,000
Number of engines transferred to the joint venture	7
Number of engines purchased						17
Capital contributions to date		25,800,000				25,800,000
Investment in joint venture		24,036,000	23,485,000			24,036,000
Number of engines in lease portfolio		26
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		22,200,000				22,200,000
Proportionate gain on sale of engines to joint venture interest (as a percent)	50.00%
Gain on sale of engines	$ 7,200,000