Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Cash Flows From Operating Activities
Net income	$ 24,344	$ 45,746
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and obsolescence allowance	13,318	12,999
Amortization of contract costs	(2,383)	(1,346)
Amortization of engine overhauls	1,305	724
Deferred income taxes	(118)	148
Loss on disposition of property and equipment	38	42
Loss on marketable securities	6,025	14
Gain on extinguishment of debt	0	(228)
Changes in operating assets and liabilities:
Accounts receivable	(16,697)	(3,530)
Notes Receivable	(7,609)	(12,971)
Spare parts and supplies	(159)	462
Prepaid expenses and other	4,623	(4,523)
Operating lease right-of-use asset	54	173
Accounts payable	(1,486)	1,658
Accrued payroll and employee benefits	(1,728)	(1,257)
Other accrued expenses	24	(20)
Long-term deferred revenue	(9,046)	(5,282)
Contract liabilities	(2,080)	(636)
Deferred revenue	(8,292)	20,634
Income taxes payable	3,487	(107)
Other long-term liabilities	(60)	0
Net Cash Provided by Operating Activities	3,560	52,700
Cash Flows From Investing Activities
Additions to property and equipment	(3,732)	(171)
Proceeds on disposition of property and equipment	7	11
Purchase of marketable securities	(958)	(160,790)
Sale of marketable securities		42,222
Net Cash Used in Investing Activities	(4,683)	(118,728)
Cash Flows From Financing Activities
Repayments of long-term debt	(1,190)	(28,873)
Dividends paid	(396)	(396)
Cancellation of stock option	(969)	0
Repurchase of common stock	(9,934)	(888)
Net Cash Used in Financing Activities	(12,489)	(30,157)
(Decrease) Increase in Cash, Cash Equivalents and Restricted Cash	(13,612)	(96,185)
Cash, Cash Equivalents and Restricted Cash, beginning of year	38,619	131,193
Cash, Cash Equivalents and Restricted Cash, end of year	$ 25,007	$ 35,008