Condensed Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Current assets:
Cash and cash equivalents	$ 159,937	$ 127,462
Customer receivables, less allowances of $9,743 and $9,465, respectively	412,932	394,169
Other receivables	5,542	21,612
Prepaid expenses and other current assets	37,039	41,410
Total current assets	615,450	584,653
Property and equipment:
Revenue equipment	1,634,854	1,591,036
Land and structures	1,588,132	1,548,079
Other fixed assets	441,957	432,146
Leasehold improvements	8,705	8,668
Total property and equipment	3,673,648	3,579,929
Accumulated depreciation	(1,222,814)	(1,175,470)
Net property and equipment	2,450,834	2,404,459
Goodwill	19,463	19,463
Other assets	58,257	59,849
Total assets	3,144,004	3,068,424
Current liabilities:
Accounts payable	78,498	73,729
Compensation and benefits	157,818	152,566
Claims and insurance accruals	51,792	49,949
Other accrued liabilities	25,872	24,805
Income taxes payable	31,305	0
Current maturities of long-term debt	0	50,000
Total current liabilities	345,285	351,049
Long-term liabilities:
Long-term debt	45,000	45,000
Other non-current liabilities	215,614	205,561
Deferred income taxes	179,354	189,960
Total long-term liabilities	439,968	440,521
Total liabilities	785,253	791,570
Commitments and Contingencies
Shareholders' equity:
Common stock - $0.10 par value, 140,000,000 shares authorized, 82,284,180 and 82,375,945 shares outstanding at March 31, 2018 and December 31, 2017, respectively	8,229	8,238
Capital in excess of par value	138,921	138,359
Retained earnings	2,211,601	2,130,257
Total shareholders' equity	2,358,751	2,276,854
Total liabilities and shareholders' equity	$ 3,144,004	$ 3,068,424