Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022
Current assets:
Cash and cash equivalents	$ 53,213	$ 80,600
Receivables:
Trade, less allowances of $497 and $500, respectively	105,501	120,702
Other	10,356	7,218
Prepaid expenses and other	27,512	27,320
Total current assets	196,582	235,840
Property and equipment:
Less accumulated depreciation	(370,103)	(346,665)
Net property and equipment	792,233	728,167
Other noncurrent assets	1,524	1,672
Total assets	990,339	965,679
Current liabilities:
Accounts payable	36,516	37,299
Insurance and claims accruals	47,017	45,747
Accrued and other current liabilities	26,709	41,264
Total current liabilities	110,242	124,310
Deferred income taxes	122,462	137,041
Noncurrent operating lease liabilities	249	409
Total liabilities	232,953	261,760
Commitments and Contingencies
Stockholders' equity:
Preferred stock, $.01 par value per share; 2,000,000 shares authorized; no shares issued and outstanding	0	0
Common stock, $.01 par value per share; 192,000,000 shares authorized; 81,312,168 shares at December 31, 2023, and 81,115,132 shares at December 31, 2022, issued and outstanding	813	811
Additional paid-in capital	49,789	47,188
Retained earnings	706,784	655,920
Total stockholders’ equity	757,386	703,919
Total liabilities and stockholders’ equity	990,339	965,679
Revenue Equipment [Member]
Property and equipment:
Revenue equipment	996,396	915,866
Land and Building [Member]
Property and equipment:
Revenue equipment	108,867	102,877
Office Equipment [Member]
Property and equipment:
Revenue equipment	$ 57,073	$ 56,089