Consolidated Condensed Statements of Cash Flows (Unaudited) (USD $) In Thousands	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Operations:
Net income	$ 16,622	$ 14,532
Adjustments to reconcile net income to net cash flows from operating activities:
Depreciation	42,358	38,533
Gain on disposition of revenue equipment	(2,819)	(812)
Deferred income taxes	8,043	3,929
Tax benefits from share-based payment arrangement exercises	164	273
Excess tax benefits from share-based payment arrangement exercises	(142)	(235)
Share-based payment arrangement compensation expense	930	801
Income before income taxes attributable to noncontrolling interest	708	365
Changes in other current operating items:
Receivables	(3,473)	(11,924)
Prepaid expenses and other	712	1,467
Accounts payable and accrued liabilities	365	251
Insurance and claims accruals	(2,724)	(1,267)
Net cash provided by operating activities	60,744	45,913
CASH FLOWS USED FOR INVESTING ACTIVITIES:
Other	111	(18)
Net cash used for investing activities	(24,072)	(71,309)
CASH FLOWS (USED FOR) PROVIDED BY FINANCING ACTIVITIES:
Borrowings under credit facility and long-term debt	35,382	121,409
Repayment of borrowings under credit facility and long-term debt	(54,728)	(95,842)
Dividends on common stock	(1,318)	(438)
Issuance of common stock from share-based payment arrangement exercises	137	234
Excess tax benefits from share-based payment arrangement exercises	142	235
Change in net checks issued in excess of cash balances	(1,066)	(1,084)
Noncontrolling interest distributions	(13)	(158)
Net cash (used for) provided by financing activities	(21,464)	24,356
NET CHANGE IN CASH AND CASH EQUIVALENTS	15,208	(1,040)
CASH AND CASH EQUIVALENTS:
Beginning of period	5,306	5,410
End of period	20,514	4,370
Cash paid (received) for:
Interest	32	165
Income taxes	(6,477)	13,596
Change in property and equipment not yet paid for	5,323	1,601
Revenue Equipment [Member]
CASH FLOWS USED FOR INVESTING ACTIVITIES:
Additions to property, plant, and equipment	(45,321)	(93,981)
Revenue Equipment [Member]
CASH FLOWS USED FOR INVESTING ACTIVITIES:
Proceeds from disposition of property, plant, and equipment	28,181	31,732
Buildings And Land, Office Equipment And Other [Member]
CASH FLOWS USED FOR INVESTING ACTIVITIES:
Additions to property, plant, and equipment	(7,116)	(9,129)
Buildings And Land, Office Equipment And Other [Member]
CASH FLOWS USED FOR INVESTING ACTIVITIES:
Proceeds from disposition of property, plant, and equipment	$ 73	$ 87