Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Cash flows from operating activities:
Net income	$ 108,682	$ 60,731
Adjustments to reconcile net income to net cash provided by operating activities:
Provision for losses on accounts receivable	367	1,338
(Reversal) deferral of gain on sales to equity method investee, net	(39)	52
Depreciation and amortization	57,512	53,881
Deferred income tax benefit	13,968	18,413
Income tax expense arising from restricted share vesting and stock options exercised	(526)	(334)
Stock-based compensation expense	6,587	9,059
Equity in income of affiliate	(25,193)	(14,782)
Return on investment in affiliated company	14,700	4,900
Gain on disposition of property and equipment	(40,322)	(3,799)
Return on investment in available-for-sale securities	0	(63)
Changes in operating assets and liabilities:
Receivables and advances	39,465	(36,544)
Prepaid expenses and other assets	(3,832)	(710)
Inventory and supplies	(193)	(204)
Insurance and claims accrual	(5,729)	(31,653)
Accounts payable and accrued expenses	(6,217)	12,933
Net cash flows provided by operating activities	159,230	73,218
Cash flows from investing activities:
Acquisition of AAT Carriers, Inc., net of cash acquired	(38,501)	0
Other investments	(241)	(13)
Redemption of available-for-sale securities	0	1,508
Acquisition of property and equipment	(100,468)	(35,285)
Proceeds from disposition of property and equipment	53,002	44,134
Net cash flows (used) provided by investing activities	(86,208)	10,344
Cash flows from financing activities:
Change in checks outstanding in excess of bank balances	(216)	(1,215)
Cash dividend	(4,287)	0
Proceeds from issuance of notes payable	95,151	0
Proceeds from exercise of stock options	384	0
Repayments of notes payable	(11,956)	(14,397)
Repayments of finance lease obligations	(5,516)	(5,626)
Proceeds under revolving credit facility	60,226	644,874
Repayments under revolving credit facility	(60,226)	(695,513)
Payment of minimum tax withholdings on stock compensation	(1,606)	(1,332)
Common stock repurchased	(84,723)	(10,348)
Net cash flows used in financing activities	(12,769)	(83,557)
Net change in cash and cash equivalents	60,253	5
Cash and cash equivalents at beginning of year	8,412	8,407
Cash and cash equivalents at end of year	68,665	8,412
Supplemental disclosure of cash flow information:
Interest, net of capitalized interest	3,306	2,762
Income taxes	16,653	10,236
Non-cash transactions during the year for:
Equipment acquired under finance leases	458	0
Contingent consideration associated with acquisition	16,210	0
Other contingent liabilities	$ (1,000)	$ (3,412)