Subsequent Event (Details)			6 Months Ended
	Jul. 13, 2015 USD ($) shares	Jul. 10, 2015 USD ($) aircraft	Jun. 30, 2015 USD ($)	Jun. 30, 2014 USD ($)
Subsequent Event [Line Items]
Payments for Repurchase of Common Stock			$ 79,415,000	$ 1,222,000
Long-term Debt			$ 435,800,000
Subsequent Event [Member]
Subsequent Event [Line Items]
Change in tax accounting method, reduction to income tax payable	$ 35,000,000
Stock Repurchased During Period, Shares | shares	180,000
Payments for Repurchase of Common Stock	$ 10.9
Airbus A321 [Member] | Subsequent Event [Member]
Subsequent Event [Line Items]
Number of aircraft delivered | aircraft		1
Long-term Debt		$ 0