Long Term Debt (Details 3) (USD $)	3 Months Ended		0 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Mar. 25, 2015 item	Jul. 17, 2014	Jan. 10, 2014	Sep. 28, 2012 engine	Dec. 31, 2014	Sep. 17, 2012
Long Term Debt
Remaining balance on notes paid off	$ 28,623,000	$ 25,506,000
Total notes payable	842,177,000						840,956,000
One-month LIBOR rate (as a percent)	0.18%						0.17%
WOLF
Long Term Debt
Number of term notes paid			2
Remaining balance on notes paid off			23,100,000
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
Fixed rate (as a percent)				2.83%
Initial term for interest payment				5 years
Percentage of the funding for the purchase of a corporate aircraft				100.00%
Total notes payable	12,600,000						12,900,000
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		7,600,000					7,700,000
Number of engines pledged as collateral						1
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	$ 14,100,000						$ 14,500,000
Basis spread on variable rate (as a percent)					2.25%
Number of engines pledged as collateral					3