Nature of Operations and Summary of Significant Accounting Policies - Long-Lived Assets (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($) aircraft	Dec. 31, 2022 USD ($) aircraft
Impairment of Long Lived and Intangible Assets
Property and equipment and related assets	$ 5,482,967	$ 5,548,480
Impairment loss of assets held for sale	2,318	$ 51,384
Number of aircraft held-for-sale | aircraft		14
Impairment on assets held for sale	2,318	$ 51,384
Held for sale | CRJ 700
Impairment of Long Lived and Intangible Assets
Impairment loss of assets held for sale	$ 2,300	$ 51,400
Number of aircraft held-for-sale | aircraft	14	14
Impairment on assets held for sale	$ 2,300	$ 51,400