CONSOLIDATED STATEMENTS OF CASH FLOWS (USD $) In Thousands	6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010
OPERATING ACTIVITIES
Net income	$ 138,689	$ 45,002
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	84,157	65,607
Stock-based compensation expense	3,821	2,642
Gain on disposition of assets, net	(1,489)	(669)
Deferred income tax provision (benefit)	7,996	(9,424)
Excess tax benefits for share-based payments	(3,419)	(596)
Changes in current assets and liabilities:
Accounts receivable	(106,220)	(87,775)
Income taxes receivable	20,066	18,294
Inventories	(14,567)	(1,845)
Prepaid expenses and other current assets	(9,093)	1,491
Accounts payable	31,557	4,929
Income taxes payable	13,293	3,895
Accrued payroll and related expenses	1,198	4,816
Accrued insurance expenses	877	286
Accrued state, local and other taxes	2,648	1,568
Other accrued expenses	(69)	(23)
Changes in working capital	(60,310)	(54,364)
Changes in other assets and liabilities:
Pension liabilities	770	268
Accrued insurance expenses	700	(246)
Other non-current assets	40	(307)
Other non-current liabilities	(130)	(109)
Net cash provided by operating activities	170,825	47,804
INVESTING ACTIVITIES
Capital expenditures	(203,763)	(56,843)
Proceeds from sale of assets	15,204	6,533
Net cash used for investing activities	(188,559)	(50,310)
FINANCING ACTIVITIES
Payment of dividends	(20,680)	(7,867)
Borrowings from notes payable to banks	402,550	173,750
Repayments of notes payable to banks	(350,700)	(163,200)
Debt issue costs for notes payable to banks	(415)
Excess tax benefits for share-based payments	3,419	596
Cash paid for common stock purchased and retired	(18,857)	(1,643)
Proceeds received upon exercise of stock options	572	64
Net cash provided by financing activities	15,889	1,700
Net decrease in cash and cash equivalents	(1,845)	(806)
Cash and cash equivalents at beginning of period	9,035	4,489
Cash and cash equivalents at end of period	7,190	3,683
Supplemental Information:
Interest paid	2,244	965
Income taxes paid, net	43,801	16,072
Change in accounts payable for capital expenditures	$ 27,531	$ 8,462