Long Term Debt - Narrative 3 (Details)					1 Months Ended	6 Months Ended
	Mar. 25, 2015 item	Jul. 17, 2014 USD ($)	Jan. 10, 2014 engine	Sep. 28, 2012 USD ($) engine	Mar. 25, 2015 USD ($)	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)	Sep. 17, 2012 USD ($)
Long Term Debt
Remaining balance on notes paid off						$ 97,521,000	$ 43,795,000
Gain on debt extinguishment						1,151,000
Total notes payable						$ 860,979,000		$ 840,956,000
One-month LIBOR rate (as a percent)						0.19%		0.17%
WOLF
Long Term Debt
Repayments of Debt					$ 23,100,000
Number of term notes paid | item	2
Prior WEST notes
Long Term Debt
Total notes payable									$ 435,900,000
Secured Debt 2.83 Percent Ten Year Member
Long Term Debt
Face amount		$ 13,400,000
Maturity term		10 years
Variable rate of debt			one-month LIBOR
Note payable at a fixed interest rate of 5.50%, maturing in September 2017. Secured by one engine.
Long Term Debt
Face amount				$ 8,700,000
Maturity term				5 years
Fixed rate (as a percent)				5.50%
Total notes payable							$ 7,400,000	$ 7,700,000
Number of engines pledged as collateral | engine				1
Term Notes Fixed Rate 2.60% to 2.97% [Member]
Long Term Debt
Face amount						$ 4,700,000
Maturity term						10 years
Initial term for interest payment						5 years
Percentage of the funding for the purchase of a corporate aircraft						100.00%
Total notes payable						$ 17,000,000		12,900,000
Note payable at a fixed interest rate of 2.25%, maturing in January 2018, secured by three engines
Long Term Debt
Maturity term			4 years
Total notes payable						$ 13,800,000		$ 14,500,000
Basis spread on variable rate (as a percent)			2.25%
Number of engines pledged as collateral | engine			3
Minimum | Term Notes Fixed Rate 2.60% to 2.97% [Member]
Long Term Debt
Fixed rate (as a percent)						2.60%
Maximum | Term Notes Fixed Rate 2.60% to 2.97% [Member]
Long Term Debt
Fixed rate (as a percent)						2.97%