Consolidated condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Cash flows provided by operating activities:
Net income	$ 22,502	$ 27,533	$ 82,821
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	29,530	26,143
Tires in service amortization	1,765	1,562
Deferred income taxes	784	1,755
Share-based payment arrangement compensation expense	354	369
Changes in other current operating items:
Receivables	9,135	(26,256)
Prepaid expenses and other	2,232	886
Accounts payable	(6,691)	5,572
Insurance and claims accruals	3,220	578
Accrued and other current liabilities	(8,353)	6,338
Net cash provided by operating activities	49,232	39,940
Cash flows (used for)/provided by investing activities:
Other	(45)	(38)
Net cash (used for)/provided by investing activities	(28,280)	409
Cash flows used for financing activities:
Dividends on common stock	(4,874)	(4,975)
Repurchase and retirement of common stock	(0)	25,000
Issuance of common stock from share-based payment arrangement exercises, deferred compensation plan distributions and vesting of performance unit awards	536	768
Employee taxes paid in exchange for shares withheld	(926)	(1,610)
Net cash used for financing activities	(5,264)	(30,817)
Net change in cash and cash equivalents	15,688	9,532
Cash and cash equivalents:
Beginning of period	80,600	56,995	66,527
End of period	96,288	66,527	$ 80,600
Supplemental non-cash disclosure:
Change in property and equipment not yet paid	2,561	4,392
Supplemental disclosure of cash flow information:
Cash paid for income taxes	22	872
Revenue Equipment [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on disposition of revenue equipment	(5,246)	(4,540)
Cash flows (used for)/provided by investing activities:
Property, plant, and equipment additions	(42,358)	(9,352)
Proceeds from Property, plant, and equipment dispositions	16,218	12,365
Buildings And Land Office Equipment And Other [Member]
Cash flows (used for)/provided by investing activities:
Property, plant, and equipment additions	(2,106)	(2,566)
Proceeds from Property, plant, and equipment dispositions	$ 11	$ 0