CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Sep. 30, 2024	Dec. 31, 2023
CURRENT ASSETS
Cash and cash equivalents	$ 150,461	$ 262,226
Short-term investments	40,639	67,842
Accounts receivable, less allowances (2024 - $9,010; 2023 - $10,346)	422,861	430,122
Other accounts receivable, less allowances (2024 - $650; 2023 - $731)	13,247	52,124
Prepaid expenses	32,400	37,034
Prepaid and refundable income taxes	21,421	24,319
Other	10,880	11,116
TOTAL CURRENT ASSETS	691,909	884,783
PROPERTY, PLANT AND EQUIPMENT
Land and structures	520,894	460,068
Revenue equipment	1,170,045	1,126,055
Service, office, and other equipment	353,880	319,466
Software	182,035	173,354
Leasehold improvements	29,648	24,429
TOTAL PROPERTY, PLANT AND EQUIPMENT, Gross	2,256,502	2,103,372
Less allowances for depreciation and amortization	1,207,110	1,188,548
PROPERTY, PLANT AND EQUIPMENT, net	1,049,392	914,824
GOODWILL	304,753	304,753
INTANGIBLE ASSETS, net	91,627	101,150
OPERATING RIGHT-OF-USE ASSETS	193,467	169,999
DEFERRED INCOME TAXES	8,293	8,140
OTHER LONG-TERM ASSETS	74,739	101,445
TOTAL ASSETS	2,414,180	2,485,094
CURRENT LIABILITIES
Accounts payable	204,696	214,004
Income taxes payable	4,808	10,410
Accrued expenses	360,738	378,029
Current portion of long-term debt	62,199	66,948
Current portion of operating lease liabilities	33,127	32,172
TOTAL CURRENT LIABILITIES	665,568	701,563
LONG-TERM DEBT, less current portion	118,312	161,990
OPERATING LEASE LIABILITIES, less current portion	192,046	176,621
POSTRETIREMENT LIABILITIES, less current portion	13,269	13,319
CONTINGENT CONSIDERATION	12,160	92,900
DEFERRED INCOME TAXES	65,738	55,785
OTHER LONG-TERM LIABILITIES	39,991	40,553
STOCKHOLDERS' EQUITY
Common stock, $0.01 par value, authorized 70,000,000 shares; issued 2024: 30,400,558 shares; 2023: 30,024,125 shares	304	300
Additional paid-in capital	327,335	340,961
Retained earnings	1,409,025	1,272,584
Treasury stock, at cost, 2024: 6,938,452 shares; 2023: 6,460,137 shares	(431,914)	(375,806)
Accumulated other comprehensive income	2,346	4,324
TOTAL STOCKHOLDERS' EQUITY	1,307,096	1,242,363
TOTAL LIABILITIES AND STOCKHOLDERS' EQUITY	$ 2,414,180	$ 2,485,094