Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash Flows from Operating Activities
Net income	$ 39,110	$ 92,626
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and obsolescence allowance	26,327	26,552
Amortization of contract costs	(4,385)	(3,593)
Amortization of engine overhauls	2,757	1,901
Deferred income taxes	7,954	(6,045)
Loss (gain) on disposition of property and equipment	181	(298)
Loss on marketable securities	8,826	1,158
Gain on extinguishment of debt	(53)	(10,363)
Changes in operating assets and liabilities:
Accounts receivable	(32,919)	2,294
Notes Receivable	28,116	(15,128)
Spare parts and supplies	(324)	(433)
Prepaid expenses and other	3,353	(3,803)
Operating lease right-of-use asset	112	218
Accounts payable	105	8,287
Accrued payroll and employee benefits	(1,896)	124
Other accrued expenses	(35)	(173)
Long-term deferred revenues	(9,046)	(21,674)
Contract liabilities	(3,054)	(707)
Deferred revenues	(19,231)	23,293
Income taxes payable	0	(107)
Other long-term liabilities	(864)	84
Net Cash Provided by Operating Activities	45,034	94,213
Cash Flows From Investing Activities
Additions to property and equipment	(5,513)	(3,637)
Proceeds on disposition of property and equipment	64	30
Purchase of marketable securities	(24,283)	(267,157)
Sale of marketable securities	0	127,629
Net Cash Used in Investing Activities	(29,732)	(143,135)
Cash Flows From Financing Activities
Repayments of long-term debt	(6,275)	(40,061)
Dividends paid on preferred stock	(792)	(792)
Repurchase of stock options	(969)	0
Repurchase of common stock	(11,703)	(2,799)
Net Cash Used in Financing Activities	(19,739)	(43,652)
Decrease in Cash, Cash Equivalents and Restricted Cash	(4,437)	(92,574)
Cash, Cash Equivalents and Restricted Cash, beginning of year	38,619	131,193
Cash, Cash Equivalents and Restricted Cash, end of year	$ 34,182	$ 38,619