CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
OPERATING ACTIVITIES
Net (loss) income	$ (26,507)	$ 102,671
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	137,914	113,308
Stock-based compensation expense	5,109	4,717
(Gain) loss on disposition of assets, net	(2,676)	3,637
Deferred income tax benefit	(26,802)	(23,255)
Excess tax benefits for share-based payments	(1,410)	(4,416)
(Increase) decrease in assets:
Accounts receivable	334,886	(128,862)
Income taxes receivable	(1,767)	(6,738)
Inventories	8,076	(12,261)
Prepaid expenses	2,713	3,049
Other current assets	1,234	(3,342)
Other non-current assets	149	(467)
Increase (decrease) in liabilities:
Accounts payable	(66,262)	33,231
Income taxes payable	3,107	535
Accrued payroll and related expenses	(25,758)	1,048
Accrued insurance expenses	1,246	552
Accrued state, local and other taxes	(854)	3,409
Other accrued expenses	(244)	139
Pension liabilities	1,009	1,167
Long-term accrued insurance expenses	1,225	1,187
Other long-term liabilities	(171)	2,179
Net cash provided by operating activities	344,217	91,488
INVESTING ACTIVITIES
Capital expenditures	(139,347)	(112,804)
Proceeds from sale of assets	6,084	11,958
Net cash used for investing activities	(133,263)	(100,846)
FINANCING ACTIVITIES
Payment of dividends	(33,599)	(45,883)
Borrowings from notes payable to banks	464,900	537,400
Repayments of notes payable to banks	(634,500)	(459,300)
Debt issue costs for notes payable to banks		(667)
Excess tax benefits for share-based payments	1,410	4,416
Cash paid for common stock purchased and retired	(4,093)	(13,144)
Net cash (used for) provided by financing activities	(205,882)	22,822
Net increase in cash and cash equivalents	5,072	13,464
Cash and cash equivalents at beginning of period	9,772	8,700
Cash and cash equivalents at end of period	14,844	22,164
Supplemental cash flows disclosure:
Interest paid, net of amounts capitalized	967	443
Income taxes paid, net	9,478	93,108
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable	$ 5,989	$ 18,205