Significant Customers - Narrative (Investment Agreement) (Details) $ / shares in Units, $ in Thousands									12 Months Ended
	Dec. 16, 2022 USD ($) shares	Oct. 07, 2022 USD ($) shares	May 29, 2022 aircraft	Dec. 07, 2021 USD ($) shares	Mar. 05, 2021 USD ($) $ / shares shares	May 29, 2020 aircraft shares	Dec. 22, 2018 aircraft shares	Mar. 08, 2016 tranche shares	Dec. 31, 2023 USD ($) aircraft $ / shares	Dec. 31, 2022 USD ($) aircraft	Dec. 31, 2021 USD ($) aircraft	Oct. 01, 2020 USD ($) shares	Sep. 08, 2020 USD ($) tranche shares	Mar. 08, 2018 shares	Feb. 09, 2016 $ / shares shares
Concentration Risk [Line Items]
Number of aircraft | aircraft									27	25
Warrants and rights outstanding, term							7 years
Stock obligations | $									$ 1,729	$ 695
Fair value adjustments of warrants | $									$ (1,000)	$ 200	$ 20,200
2016 Investment Agreement
Concentration Risk [Line Items]
Number of warrant tranches | tranche								3					3
Class of warrant or right, ownership percentage, maximum								19.90%					19.90%
Class of warrant or right, number of securities called by warrants or rights (in shares)															14,900,000
Exercise price (in dollars per share) | $ / shares															$ 9.73
Amended 2016 Investment Agreement
Concentration Risk [Line Items]
Class of warrant or right, ownership percentage, maximum	19.90%
Exercise price (in dollars per share) | $ / shares					$ 27.27
Class of warrant or right, cashless exercise, exercised (in shares)					865,548
Class of warrant or right, cashless exercise, forfeited (in shares)					480,047
Class of warrant or right, exercised (in shares)					13,562,897
Proceeds from warrant exercises | $					$ 132,000
Stock repurchased during period (in shares)	260,000	250,000
Stock repurchased during period, value | $	$ 7,000	$ 5,900
2018 Investment Agreement
Concentration Risk [Line Items]
Class of warrant or right, number of securities called by warrants or rights (in shares)						2,900,000
Exercise price (in dollars per share) | $ / shares									$ 21.53
Lessee, number of leased aircraft | aircraft						5
Lessee, operating lease, option to extend							five years
Lessee, operating lease, additional option to extend							3 years
Number of additional leased aircraft | aircraft							10
Lessor, leased aircraft, number of lease extensions | aircraft							20
2018 Investment Agreement | B-767-300
Concentration Risk [Line Items]
Number of aircraft | aircraft							10
Lessor, number of leased aircraft | aircraft			12				10				10
Lessor, leased aircraft, option to extend, term							3 years
Lessee, number of leased aircraft | aircraft							8
Lessor, leased aircraft, extended term							3 years
2018 Investment Agreement | B-767-200
Concentration Risk [Line Items]
Lessor, number of leased aircraft | aircraft							12
Lessor, leased aircraft, term							2 years
Lessor, leased aircraft, option to extend, term							3 years
2018 Investment Agreement | Common Stock
Concentration Risk [Line Items]
Common shares, vested (in shares)						7,000,000	14,800,000
2020 Investment Agreement
Concentration Risk [Line Items]
Exercise price (in dollars per share) | $ / shares									$ 20.40
Lessor, leased aircraft, term						10 years
2020 Investment Agreement | B-767-300
Concentration Risk [Line Items]
Lessor, number of leased aircraft | aircraft			12			12				11
Tranche One | 2016 Investment Agreement
Concentration Risk [Line Items]
Class of warrant or right, number of securities called by warrants or rights (in shares)								12,810,000
Class of warrant or right, vested (in shares)								7,690,000
Tranche Two | 2016 Investment Agreement
Concentration Risk [Line Items]
Class of warrant or right, number of securities called by warrants or rights (in shares)														1,590,000
Class of warrant or right, vested (in shares)								5,120,000
Tranche Three | 2016 Investment Agreement
Concentration Risk [Line Items]
Class of warrant or right, number of securities called by warrants or rights (in shares)													500,000
Class of warrant or right, securities, fair value | $													$ 221,000
Class of warrant or right, number of securities granted for purchase (in shares)													500,000
Tranche Three | 2018 Investment Agreement
Concentration Risk [Line Items]
Common shares, vested (in shares)												14,800,000
Class of warrant or right, securities, fair value | $												$ 154,000
Tranche Three | 2020 Investment Agreement
Concentration Risk [Line Items]
Common shares, vested (in shares)				7,000,000
Reclassification of liability to equity | $				$ 82,400