Condensed Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 8,169	$ 30,174
Customer receivables, less allowances of $9,471 and $8,067, respectively	322,395	248,069
Other receivables	7,086	10,225
Prepaid expenses	29,841	21,262
Deferred income taxes	27,110	23,249
Total current assets	394,601	332,979
Property and equipment:
Revenue equipment	1,163,523	1,009,936
Land and structures	1,044,678	990,256
Other fixed assets	320,084	266,563
Leasehold improvements	7,096	6,378
Total property and equipment	2,535,381	2,273,133
Accumulated depreciation	(804,487)	(730,074)
Net property and equipment	1,730,894	1,543,059
Goodwill	19,463	19,463
Other assets	43,581	36,588
Total assets	2,188,539	1,932,089
Current liabilities:
Accounts payable	47,285	36,788
Compensation and benefits	123,220	97,187
Claims and insurance accruals	41,948	38,784
Other accrued liabilities	25,826	21,480
Income taxes payable	12,608	2,168
Current maturities of long-term debt	35,714	35,715
Total current liabilities	286,601	232,122
Long-term liabilities:
Long-term debt	148,203	155,714
Other non-current liabilities	138,180	123,054
Deferred income taxes	185,828	189,117
Total long-term liabilities	472,211	467,885
Total liabilities	758,812	700,007
Commitments and Contingencies
Shareholders' equity:
Common stock - $0.10 par value, 140,000,000 shares authorized, 86,164,917 shares outstanding at September 30, 2014 and December 31, 2013	8,616	8,616
Capital in excess of par value	134,401	134,401
Retained earnings	1,286,710	1,089,065
Total shareholders' equity	1,429,727	1,232,082
Total liabilities and shareholders' equity	$ 2,188,539	$ 1,932,089