Consolidated Statements Of Cash Flows (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash flows from operating activities:
Net income	$ 6,188	$ 3,205
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization of property, equipment and intangibles	54,697	55,085
Amortization of debt issuance costs, original issue discount, and losses on terminated swaps	4,260	6,117
Gain on disposal of property and equipment less write-off of totaled tractors	(4,280)	(1,998)
Impairment of property and equipment	1,065
Equity losses of investee	78
Deferred income taxes	(5,712)	2,426
Provision for allowance for losses on accounts receivable	138	85
Loss on debt extinguishment	20,940
Non-cash equity compensation	1,267	2,424
Increase (decrease) in cash resulting from changes in:
Accounts receivable	(15,293)	(37,872)
Inventories and supplies	(5,000)	(1,849)
Prepaid expenses and other current assets	(3,322)	(4,348)
Other assets	123	5,360
Accounts payable, accrued and other liabilities	15,023	31,240
Net cash provided by operating activities	70,172	59,875
Cash flows from investing activities:
Decrease (increase) in restricted cash	10,718	(510)
Change in fixed maturity securities-restricted	(11,086)
Funding of GTI note receivable	(7,500)
Proceeds from sale of property and equipment	33,858	5,880
Capital expenditures	(44,246)	(39,534)
Payments received on notes receivable	1,980	1,647
Expenditures on assets held for sale	(1,719)	(3,085)
Payments received on assets held for sale	1,760	4,053
Payments received on equipment sale receivables	5,466
Other investing activities	(500)
Net cash used in investing activities	(11,269)	(31,549)
Cash flows from financing activities:
Proceeds from issuance of Class A common stock, net of issuance costs		62,994
Repayment of long-term debt and capital leases	(70,523)	(81,765)
Payment of deferred loan costs	(5,932)
Borrowings under accounts receivable securitization	89,000	22,000
Repayment of accounts receivable securitization	(106,000)	(57,500)
Proceeds from exercise of stock options	263
Income tax deficiency from exercise of stock options	(111)
Net cash used in financing activities	(93,303)	(54,271)
Net decrease in cash and cash equivalents	(34,400)	(25,945)
Cash and cash equivalents at beginning of period	82,084	47,494
Cash and cash equivalents at end of period	47,684	21,549
Cash paid during the period for:
Interest	27,557	7,391
Income taxes	2,220	842
Non-cash investing activities:
Equipment sales receivables	700	844
Equipment purchase accrual	18,870	9,840
Notes receivable from sale of assets	685	3,579
Non-cash financing activities:
Accrued deferred loan costs	120
Capital lease additions	$ 17,099	$ 705