Property and Equipment Property and Equipment Narrative (Details) - USD ($) $ in Thousands	1 Months Ended	9 Months Ended
	Aug. 31, 2017	Sep. 30, 2017	Oct. 01, 2016	Dec. 31, 2016
Property, Plant and Equipment [Line Items]
Depreciation		$ 10,800	$ 9,500
Depreciation and amortization		14,384	$ 12,355
Total property and equipment		243,698		$ 204,229
Accumulated depreciation		$ 79,119		$ 68,233
Aircraft
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Additions	$ 25,300