Organization and Summary of Significant Accounting Policies - Impairment of Long-Lived Asset Reclassified to Held for Sale (Details) - USD ($) $ in Thousands	1 Months Ended	3 Months Ended	12 Months Ended
	Dec. 31, 2018	Mar. 31, 2019	Dec. 31, 2019
Property, Plant and Equipment [Line Items]
Gain on sale of aircraft			$ 357
Air Transportation Equipment
Property, Plant and Equipment [Line Items]
Gain on sale of aircraft		$ 357
Air Transportation Equipment | Other Assets
Property, Plant and Equipment [Line Items]
Carrying amount of aircraft	$ 10,500
Air Transportation Equipment | Aircraft under Non-Binding Letters of Intent
Property, Plant and Equipment [Line Items]
Expected proceeds from sale of aircraft	$ 10,900