Note C - Significant Customers (Details Textual) $ / shares in Units, $ in Thousands					3 Months Ended
	May 06, 2024 $ / shares shares	Aug. 14, 2023 USD ($) shares	May 29, 2020 $ / shares shares	Dec. 22, 2018 $ / shares shares	Mar. 31, 2024 USD ($)	Mar. 31, 2023 USD ($)	Sep. 30, 2022	Dec. 31, 2023 USD ($)	Dec. 31, 2021	Dec. 31, 2020	Dec. 20, 2018 shares
Stock Repurchased During Period, Shares (in shares)		5,435,777
Payments for Repurchase of Common Stock | $					$ (0)	$ 21,918
Warrants With Investment Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)			7,000,000	14,800,000							14,800,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares			$ 20.4	$ 21.53
Class of Warrant or Right, Additional Number of Securities Called by Warrants or Rights (in shares)			2,900,000
Lessee, Number of Leased Aircraft			5
Warrants and Rights Outstanding | $					1,600			$ 1,700
Fair Value Adjustment of Warrants | $					$ (100)	$ (800)
Warrants With Investment Agreement [Member] | Subsequent Event [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	21,800,000
B-767-300 [Member]
Lessor, Number of Leased Aircraft			12						11	10
Lessor, Leased Aircraft, Lease Term (Year)			10 years
B-767 [Member]
Number of Additional Leased Aircraft										10
Lessor, Leased Aircraft, Number of Lease Extensions										20
DHL [Member] | B-767-200 [Member]
Lessor, Number of Leased Aircraft					1
DHL [Member] | B-767-300 [Member]
Lessor, Number of Leased Aircraft					13
DHL [Member] | B-767 [Member]
Number of Aircraft Operated							4
ASI [Member] | B-767-200 [Member]
Lessor, Number of Leased Aircraft				12
Lessor, Leased Aircraft, Lease Term (Year)				2 years
Lessor, Leased Aircraft, Option to Extend, Term (Year)				3 years
ASI [Member] | B-767-300 [Member]
Lessor, Number of Leased Aircraft				8
Number of Aircraft Operated				10
Lessor, Leased Aircraft, Option to Extend, Term (Year)				3 years
ATSA [Member]
Warrants and Rights Outstanding, Term (Year)	5 years
ATSA [Member] | The 2024 Subsequent Warrant [Member] | Subsequent Event [Member]
Warrants and Rights Outstanding, Term (Year)	7 years
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	2,900,000
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share) | $ / shares	$ 12.96
ATSA [Member] | The 2024 Subsequent Warrant [Member] | Subsequent Event [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	728,750
ATSA [Member] | B-767-300 [Member] | Subsequent Event [Member]
Lessor, Number of Leased Aircraft	10
Lessor, Leased Aircraft, Option to Extend, Term (Year)	5 years
Amazon [Member]
Stock Repurchased During Period, Shares (in shares)		1,177,000
Payments for Repurchase of Common Stock | $		$ 22,900
Amazon [Member] | Subsequent Event [Member]
Lessor, Leased Aircraft, Option to Extend, Term (Year)	3 years
Amazon [Member] | Third Subsequent Warrant [Member] | Subsequent Event [Member]
Warrants and Rights Outstanding, Term (Year)	7 years
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	2,900,000
Amazon [Member] | Third Subsequent Warrant [Member] | Subsequent Event [Member] | Share-Based Payment Arrangement, Tranche One [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	291,500
Amazon [Member] | Third Subsequent Warrant [Member] | Subsequent Event [Member] | Share-Based Payment Arrangement, Tranche Two [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)	72,875