Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Adjustments, Noncash Items, to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities	$ 336	$ 655
CASH FLOWS FROM OPERATING ACTIVITIES
Net cash provided by operating activities	30,853	45,538
Net earnings	2,600	7,515
Adjustments to reconcile net earnings to net cash provided by operating activities:
Depreciation and amortization	25,167	27,557
Equity-based compensation expense	781	17
Deferred tax expense	(240)	4,375
Employee benefit plans	312	(788)
Changes in working capital, net	1,244	(1,089)
Change in taxes receivable, net	1,463	5,597
Other Operating Activities, Cash Flow Statement	(810)	1,699
CASH FLOWS FROM INVESTING ACTIVITIES
Additions to plant and equipment	(48,430)	(42,247)
Payments for (Proceeds from) Other Investing Activities	768	368
Net cash used for investing activities	(47,662)	(41,879)
CASH FLOWS FROM FINANCING ACTIVITIES
Purchase of treasury stock	0	(4,875)
Proceeds from (Repayments of) Short-term Debt	87,325	91,000
Payments of Debt Issuance Costs	(73,825)	(96,000)
Payment of tax withholdings on equity-based payment arrangements	(220)
Proceeds from (Payments for) Other Financing Activities	(365)	(790)
Net cash (used for) provided by financing activities	13,135	(10,665)
Decrease in cash and cash equivalents	(3,674)	(7,006)
Cash at beginning of period	15,738	23,001
Cash at end of period	12,064	15,995
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest, net of amounts capitalized	13,927	14,418
Cash paid for income taxes	142	206
Cash received from income tax refunds	1,873	5,551
Changes in accrued plan and equipment	$ 1,317	$ (443)