Consolidated condensed Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Cash flows provided by operating activities:
Net income	$ 27,533	$ 18,006	$ 67,422
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation	26,143	25,687
Tires in service amortization	1,562	1,642
Deferred income taxes	1,755	1,085
Share-based payment arrangement compensation expense	369	336
Changes in other current operating items:
Receivables	(26,256)	(4,241)
Prepaid expenses and other	886	1,445
Accounts payable	5,572	677
Insurance and claims accruals	578	2,117
Accrued and other current liabilities	6,338	(1,200)
Net cash provided by operating activities	39,940	43,570
Cash flows provided by/(used for) investing activities:
Other	(38)	(37)
Net cash provided by/(used for) investing activities	409	(17,417)
Cash flows used for financing activities:
Repurchase and retirement of common stock	(25,000)	0
Dividends on common stock	(4,975)	(3,311)
Issuance of common stock from share-based payment arrangement exercises, deferred compensation plan distributions and vesting of performance unit awards	768	161
Employee taxes paid in exchange for shares withheld	(1,610)	(547)
Net cash used for financing activities	(30,817)	(3,697)
Net change in cash and cash equivalents	9,532	22,456
Cash and cash equivalents:
Beginning of period	56,995	66,127	88,583
End of period	66,527	88,583	$ 56,995
Supplemental non-cash disclosure:
Change in property and equipment not yet paid	4,392	5,505
Supplemental disclosure of cash flow information:
Cash paid for income taxes	872	1,350
Revenue Equipment [Member]
Adjustments to reconcile net income to net cash provided by operating activities:
Gain on disposition of revenue equipment	(4,540)	(1,984)
Cash flows provided by/(used for) investing activities:
Property, plant and equipment additions	(9,352)	(30,226)
Proceeds from revenue equipment dispositions	12,365	13,896
Buildings And Land Office Equipment And Other [Member]
Cash flows provided by/(used for) investing activities:
Property, plant and equipment additions	$ (2,566)	$ (1,050)