Condensed Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Current assets:
Cash and cash equivalents	$ 339,761	$ 401,430
Short-term investments	224,899	330,274
Customer receivables, less allowances of $10,348 and $8,979, respectively	591,783	444,653
Other receivables	62,266	9,569
Prepaid expenses and other current assets	60,143	57,413
Total current assets	1,278,852	1,243,339
Property and equipment:
Revenue equipment	2,096,973	1,885,649
Land and structures	2,352,569	2,218,290
Other fixed assets	502,907	475,264
Leasehold improvements	13,055	12,226
Total property and equipment	4,965,504	4,591,429
Accumulated depreciation	(1,855,390)	(1,677,398)
Net property and equipment	3,110,114	2,914,031
Other assets	224,154	212,040
Total assets	4,613,120	4,369,410
Current liabilities:
Accounts payable	135,044	68,511
Compensation and benefits	244,168	191,303
Claims and insurance accruals	58,253	53,092
Other accrued liabilities	96,826	51,513
Income taxes payable		8,711
Total current liabilities	534,291	373,130
Long-term liabilities:
Long-term debt	99,943	99,931
Other non-current liabilities	330,321	349,851
Deferred income taxes	228,667	220,210
Total long-term liabilities	658,931	669,992
Total liabilities	1,193,222	1,043,122
Commitments and contingent liabilities
Shareholders’ equity:
Common stock - $0.10 par value, 280,000,000 shares authorized, 115,011,172 and 117,057,696 shares outstanding at September 30, 2021 and December 31, 2020, respectively	11,501	11,706
Capital in excess of par value	170,340	226,451
Retained earnings	3,238,057	3,088,131
Total shareholders’ equity	3,419,898	3,326,288
Total liabilities and shareholders’ equity	$ 4,613,120	$ 4,369,410