Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022
Cash Flows from Operating Activities
Net (loss) income	$ (11,975)	$ 32,366
Adjustments to reconcile net (loss) income to net cash (used) in/provided by operating activities:
Depreciation, amortization and obsolescence allowance	19,125	19,957
Amortization of contract costs	(1,654)	(3,314)
Amortization of engine overhauls	2,485	2,098
Deferred income taxes	(3,566)	(118)
Loss on disposition of property and equipment	219	62
Loss on marketable securities	10	9,774
Gain on extinguishment of debt	(70)	(53)
Changes in operating assets and liabilities:
Receivables, net	(51)	(25,850)
Notes receivable	(1,641)	(12,747)
Spare parts and supplies	(450)	(149)
Prepaid expenses and other	471	3,699
Operating lease right-of-use asset	140	41
Accounts payable	(5,870)	(3,467)
Accrued payroll and employee benefits	246	(1,828)
Other accrued expenses	29	81
Long-term deferred revenue	0	(9,046)
Contract liabilities	843	(2,534)
Deferred revenues	(16,561)	(13,474)
Income taxes payable	0	4,633
Other long-term liabilities	(222)	35
Net Cash (Used) in/Provided by Operating Activities	(18,492)	166
Cash Flows from Investing Activities
Additions to property and equipment	(3,017)	(2,963)
Proceeds on disposition of property and equipment	19	10
Purchase of marketable securities	(2,745)	(1,921)
Sale of marketable securities	20,000	0
Net Cash Provided by/(Used) in Investing Activities	14,257	(4,874)
Cash Flows from Financing Activities
Repayment of long-term debt	(8,598)	(2,184)
Dividends paid on preferred stock	(915)	(594)
Cancellation of stock option	0	(969)
Repurchased stock	(3,888)	(10,733)
Net Cash Used in Financing Activities	(13,401)	(14,480)
Decrease in Cash, Cash Equivalents and Restricted Cash	(17,636)	(19,188)
Cash, Cash Equivalents and Restricted Cash, beginning of period	34,182	38,619
Cash, Cash Equivalents and Restricted Cash, end of period	$ 16,546	$ 19,431