CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
OPERATING ACTIVITIES
Net (loss) income	$ (87,111)	$ 175,402	$ 162,511
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation, amortization and other non-cash charges	172,607	166,789	166,558
Stock-based compensation expense	8,630	9,419	11,090
Gain on disposition of assets, net	2,645	3,344	4,530
Gain due to insurance recovery		(9,646)
Gain due to benefit plan financing arrangement	(126)	(1,020)
Deferred income tax (benefit) provision	(22,225)	21,395	(42,609)
Impairment and other charges, net	73,560
(Increase) decrease in assets:
Accounts receivable	81,094	53,982	(208,642)
Income taxes receivable	11,687	4,410	16,931
Inventories	20,962	(15,660)	(6,275)
Prepaid expenses	(692)	(778)	(2,272)
Other current assets	300	3,375	(1,222)
Other non-current assets	(3,024)	1,494	(4,779)
Increase (decrease) in liabilities:
Accounts payable	(42,241)	(7,754)	29,176
Income taxes payable	(3,172)	1,482	(1,705)
Accrued payroll and related expenses	(6,103)	2,193	11,408
Accrued insurance expenses	1,357	884	1,200
Accrued state, local and other taxes	(654)	(5,574)	5,561
Other accrued expenses	(2,089)	(994)	(5,335)
Pension liabilities	6,575	(7,862)	4,398
Long-term accrued insurance expenses	1,968	1,696	839
Other long-term liabilities	483	(880)	1,401
Net cash provided by operating activities	209,141	389,009	133,704
INVESTING ACTIVITIES
Capital expenditures	(250,629)	(242,610)	(117,509)
Proceeds from sale of assets	14,841	13,237	13,123
Proceeds from insurance recovery		9,646
Proceeds from benefit plan financing arrangement	507	2,218
Re-investment in benefit plan financing arrangement	(507)	(2,218)
Net cash used for investing activities	(235,788)	(219,727)	(104,386)
FINANCING ACTIVITIES
Payment of dividends	(32,231)	(101,069)	(43,319)
Cash paid for common stock purchased and retired	(7,361)	(43,001)	(26,784)
Net cash used for financing activities	(39,592)	(144,070)	(70,103)
Net (decrease) increase in cash and cash equivalents	(66,239)	25,212	(40,785)
Cash and cash equivalents at beginning of year	116,262	91,050	131,835
Cash and cash equivalents at end of year	$ 50,023	$ 116,262	$ 91,050