Restructuring Property, plant and equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2016	Dec. 25, 2016	Dec. 31, 2015
Property, Plant and Equipment [Line Items]
Other Depreciation and Amortization	$ 6,500
Property, plant and equipment, net		$ 227,403	$ 227,403	$ 234,646
Air Transportation Equipment [Member]
Property, Plant and Equipment [Line Items]
Gain (Loss) on Disposition of Property Plant Equipment, Excluding Oil and Gas Property and Timber Property	200
Selling, General and Administrative Expenses [Member]
Property, Plant and Equipment [Line Items]
Other Depreciation and Amortization	$ 1,100