Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Cash flows from continuing operating activities
Net loss	$ (61,911)	$ (63,417)	$ (72,226)
Adjustments to reconcile net loss to net cash provided (used) by continuing operating activities:
Deferred income taxes	(4,778)	(20,895)	1,825
Depreciation and amortization of property, plant and equipment	69,581	68,325	70,266
Amortization of intangible and other assets	1,260	1,249	2,361
Loss (gain) on sales of property and equipment	636	678	(1,637)
Loss associated with assets held for sale		9,701
Stock-based compensation	1,761	2,220	8,358
Loss associated with commodity contracts	1,613
Charge on extinguishment of debt			5,951
Other	4,081	2,794	2,098
Cash provided (used) by changes in assets and liabilities (net of effects of discontinued operations):
Accounts receivable	(4,702)	8,800	(2,167)
Inventories	3,550	6,092	(6,698)
Other supplies, prepaid items and other	84	(934)	564
Accounts payable	(6,561)	(7,987)	14,208
Accrued interest	1,578	586	(6,919)
Other current and noncurrent liabilities	(8,705)	(5,113)	1,638
Net cash provided (used) by continuing operating activities	(2,513)	2,099	17,622
Cash flows from continuing investing activities
Expenditures for property, plant and equipment	(30,471)	(36,081)	(37,050)
Proceeds from vendor settlements associated with property, plant and equipment	1,647
Proceeds from sales of property and equipment	394	61	6,660
Proceeds from property insurance recovery associated with property, plant and equipment			1,531
Net proceeds from sale of discontinued operations			2,730
Other investing activities	4	95	389
Net cash used by continuing investing activities	(28,426)	(35,925)	(25,740)
Cash flows from continuing financing activities
Proceeds from revolving debt facility	30,000	5,000	10,000
Payments on revolving debt facility	(30,000)	(15,000)
Net proceeds from 9.625% senior secured notes		35,086	390,473
Payments on senior secured notes			(375,000)
Proceeds from other long-term debt	42,570	20,219
Payments on other long-term debt	(21,356)	(14,073)	(9,170)
Payments of debt-related costs, including extinguishment and modification costs	(124)	(1,065)	(10,974)
Proceeds from short-term financing	14,589	12,179	10,865
Payments on short-term financing	(10,941)	(10,828)	(10,872)
Taxes paid on equity awards	(326)	(949)	(2,018)
Payments of preferred stock modification costs			(2,777)
Proceeds from exercises of stock options			20
Net cash provided by continuing financing activities	24,412	30,569	547
Net decrease in cash and cash equivalents	(6,527)	(3,257)	(7,571)
Cash and cash equivalents at beginning of year	22,791	26,048	33,619
Cash and cash equivalents at end of year	$ 16,264	$ 22,791	$ 26,048