CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
OPERATING ACTIVITIES
Net (loss) income	$ (32,511)	$ 7,548
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	61,418	67,555
Stock-based compensation expense	2,660	2,523
Gain on disposition of assets, net	(1,256)	(958)
Deferred income tax benefit	(8,423)	(18,413)
Excess tax benefits for share-based payments	(403)	(1,460)
(Increase) decrease in assets:
Accounts receivable	56,887	203,706
Income taxes receivable	10,501	16,063
Inventories	3,674	1,217
Prepaid expenses	1,581	621
Other current assets	241	806
Other non-current assets	117	225
Increase (decrease) in liabilities:
Accounts payable	(29,410)	(57,944)
Income taxes payable	1,065	783
Accrued payroll and related expenses	(595)	(22,346)
Accrued insurance expenses	668	862
Accrued state, local and other taxes	1,140	(841)
Other accrued expenses	2,069	(17)
Pension liabilities	(732)	359
Long-term accrued insurance expenses	(1,099)	769
Other long-term liabilities	(14,120)	(466)
Net cash provided by operating activities	53,472	200,592
INVESTING ACTIVITIES
Capital expenditures	(9,581)	(103,492)
Proceeds from sale of assets	2,010	2,899
Net cash used for investing activities	(7,571)	(100,593)
FINANCING ACTIVITIES
Payment of dividends		(22,762)
Borrowings from notes payable to banks		265,400
Repayments of notes payable to banks		(334,300)
Excess tax benefits for share-based payments	403	1,460
Cash paid for common stock purchased and retired	(3,191)	(4,093)
Net cash used for financing activities	(2,788)	(94,295)
Net increase in cash and cash equivalents	43,113	5,704
Cash and cash equivalents at beginning of period	65,196	9,772
Cash and cash equivalents at end of period	108,309	15,476
Supplemental cash flows disclosure:
Interest paid, net of amounts capitalized	282	608
Income taxes (received) paid, net	(32,487)	4,423
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable	$ 1,862	$ 13,413