CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
OPERATING ACTIVITIES
Net (loss) income	$ (185,516)	$ 5,432
Adjustments to reconcile net (loss) income to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	58,924	86,809
Stock-based compensation expense	4,114	4,888
Gain on disposition of assets, net	4,013	4,637
Deferred income tax benefit	(36,723)	(12,579)
Impairment and other non-cash charges	206,264
(Increase) decrease in assets:
Accounts receivable	133,223	(34,337)
Income taxes receivable	(22,762)	31,158
Inventories	7,320	11,701
Prepaid expenses	4,601	1,614
Other current assets	235	600
Other non-current assets	(423)	(3,609)
Increase (decrease) in liabilities:
Accounts payable	(27,451)	2,764
Income taxes payable	(1,099)	(3,647)
Accrued payroll and related expenses	(6,373)	(2,758)
Accrued insurance expenses	(1,228)	1,167
Accrued state, local and other taxes	1,304	2,753
Other accrued expenses	(4,966)	(349)
Pension liabilities	(610)	4,497
Long-term accrued insurance expenses	(1,045)	2,208
Other long-term liabilities	(1,677)	(245)
Net cash provided by operating activities	122,099	93,430
INVESTING ACTIVITIES
Capital expenditures	(38,659)	(132,253)
Proceeds from sale of assets	12,740	9,776
Net cash used for investing activities	(25,919)	(122,477)
FINANCING ACTIVITIES
Payment of dividends		(32,224)
Cash paid for common stock purchased and retired	(798)	(7,349)
Net cash used for financing activities	(798)	(39,573)
Net increase (decrease) in cash and cash equivalents	95,382	(68,620)
Cash and cash equivalents at beginning of period	50,023	116,262
Cash and cash equivalents at end of period	145,405	47,642
Supplemental cash flows disclosure:
Income taxes refund, net	(9,847)	(12,125)
Supplemental disclosure of noncash investing activities:
Capital expenditures included in accounts payable	$ 2,185	$ 31,407