Investments in Other Companies (Details) $ / shares in Units, $ in Thousands	1 Months Ended		3 Months Ended		12 Months Ended
	Jan. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2024 USD ($) item	Mar. 31, 2023 USD ($)	Dec. 31, 2023 USD ($) shares	Dec. 31, 2022 USD ($) $ / shares shares
Long-term debt		$ 3,006,052	$ 2,895,829		$ 3,006,052
Aircraft maintenance, materials and repairs			$ 145,415	$ 142,226
Fair Value, Net Derivative Asset (Liability), Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]			Other Nonoperating Income (Expense)
Aero Engines, LLC. ("Aero Engines")
Payments to acquire interest in joint venture			$ 26,600
Long-term debt			0
Aero Engines, LLC. ("Aero Engines") | Other Assets
Investment balance in other companies			25,300
Aero Engines, LLC. ("Aero Engines") | Other income (loss), net
Company's portion of income (loss) generated by other companies			$ 200
Contour Airlines
Investment ownership (as a percent)		9.90%	25.00%		9.90%
Aircraft maintenance, materials and repairs			$ 14,000
Aircraft and collectible years			4 years
Payments to acquire equity method investment	$ 15,100	$ 9,900
Number of Board of Directors Seat Held | item			1
Total Number of Board of Directors Seat | item			5
Percentage of Board of Directors Seat Held			20.00%
Contour Airlines | Other Assets
Investment balance in other companies			$ 25,000
Contour Airlines | Other income (loss), net
Company's portion of income (loss) generated by other companies			(100)
Eve Holdings, Inc. ("Eve")
Warrants to purchase shares | shares						1,500,000
Warrants exercise price (in dollars per share) | $ / shares						$ 0.01
Initial investment						$ 10,000
Unrealized loss			3,500
Eve Holdings, Inc. ("Eve") | Level 3
Beginning balance	$ 12,477		12,477
Unrealized loss			2,731
Ending balance		$ 12,477	9,746		$ 12,477
Eve Holdings, Inc. ("Eve") | Level 3 | Black Scholes Option Pricing Model | Volatility
Measurement input						0.52
Eve Holdings, Inc. ("Eve") | Put option
Shares obtained | shares						1,000,000
Shares sold | shares					600,411
Shares reduced | shares					600,411
Eve Holdings, Inc. ("Eve") | Other Assets
Investment balance in other companies			$ 11,900
Eve Holdings, Inc. ("Eve") | Class A common stock
Number of shares acquired | shares						1,000,000