CONSOLIDATED STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
OPERATING ACTIVITIES
Net income (loss)	$ 3,634	$ (32,511)
Adjustments to reconcile net income (loss) to net cash (used for) provided by operating activities:
Depreciation, amortization and other non-cash charges	45,412	61,418
Stock-based compensation expense	2,687	2,660
Gain on disposition of assets, net	(1,517)	(1,256)
Deferred income tax benefit	(11,667)	(8,423)
Excess tax benefits for share-based payments		(403)
(Increase) decrease in assets:
Accounts receivable	(77,406)	56,887
Income taxes receivable	8,713	10,501
Inventories	(3,595)	3,674
Prepaid expenses	(179)	1,581
Other current assets	(429)	241
Other non-current assets	(749)	117
Increase (decrease) in liabilities:
Accounts payable	19,775	(29,410)
Income taxes payable	(1,124)	1,065
Accrued payroll and related expenses	5,399	(595)
Accrued insurance expenses	582	668
Accrued state, local and other taxes	1,652	1,140
Other accrued expenses	(4,938)	2,069
Pension liabilities	986	(732)
Long-term accrued insurance expenses	345	(1,099)
Other long-term liabilities	(30)	(14,120)
Net cash (used for) provided by operating activities	(12,449)	53,472
INVESTING ACTIVITIES
Capital expenditures	(11,707)	(9,581)
Proceeds from sale of assets	2,493	2,010
Net cash used for investing activities	(9,214)	(7,571)
FINANCING ACTIVITIES
Excess tax benefits for share-based payments		403
Cash paid for common stock purchased and retired	(5,674)	(3,191)
Net cash used for financing activities	(5,674)	(2,788)
Net (decrease) increase in cash and cash equivalents	(27,337)	43,113
Cash and cash equivalents at beginning of period	131,835	65,196
Cash and cash equivalents at end of period	104,498	108,309
Supplemental cash flows disclosure:
Interest paid, net of amounts capitalized		282
Income taxes paid (received), net	2,199	(32,487)
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable	$ 5,322	$ 1,862