Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Cash flows from operating activities:
Net earnings	$ 117,740	$ 127,493
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	179,476	182,996
Noncash lease expense	24,404	26,497
Share-based compensation	18,444	18,409
Loss on sale of revenue equipment and other	6,476	7,271
Deferred income taxes	(36,058)	16,788
Changes in operating assets and liabilities:
Trade accounts receivable	21,337	62,797
Other assets	35,870	92,021
Trade accounts payable	(3,408)	(65,398)
Income taxes payable or receivable	72,573	27,694
Claims accruals	16,444	5,131
Accrued payroll and other accrued expenses	(49,106)	(35,232)
Net cash provided by operating activities	404,192	466,467
Cash flows from investing activities:
Additions to property and equipment	(245,812)	(203,387)
Net proceeds from sale of equipment	20,762	37,205
Business acquisition	0	3,785
Net cash used in investing activities	(225,050)	(162,397)
Cash flows from financing activities:
Proceeds from issuances of long-term debt	750,000	0
Payments on long-term debt	(500,000)	(250,000)
Proceeds from revolving lines of credit and other	656,900	407,600
Payments on revolving lines of credit and other	(805,602)	(367,600)
Purchase of treasury stock	(234,129)	(25,140)
Stock repurchased for payroll taxes and other	(5,883)	(13,671)
Dividends paid	(44,004)	(44,418)
Net cash used in financing activities	(182,718)	(293,229)
Net change in cash and cash equivalents	(3,576)	10,841
Cash and cash equivalents at beginning of period	46,983	53,344
Cash and cash equivalents at end of period	43,407	64,185
Supplemental disclosure of cash flow information:
Interest	26,307	28,994
Income taxes	3,747	5,351
Noncash investing activities
Accruals for equipment received	$ 72,117	$ 104,467