Investment in Other Companies (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) engine
Number of spare engines sold to Aero Engines | engine	15
Aero Engines, LLC.
Payments to acquire interest in joint venture	$ 22,300
Investment ownership (as a percent)	75.00%
Number of spare engines purchased | engine	15
Long-term debt	$ 0
Investment balance in Aero Engines	25,500
Additional interest in Joint venture	1,000
Company's portion of income generated by Aero Engines	$ 1,600