CONSOLIDATED BALANCE SHEETS (Unaudited) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
ASSETS
Cash and cash equivalents	$ 104,498	$ 131,835
Accounts receivable, net of allowance for doubtful accounts of $2,956 in 2017 and $2,553 in 2016	246,583	169,166
Inventories	111,945	108,316
Income taxes receivable	48,461	57,174
Prepaid expenses	6,897	6,718
Other current assets	6,269	5,848
Total current assets	524,653	479,057
Property, plant and equipment, less accumulated depreciation of $1,631,602 in 2017 and $1,595,508 in 2016	465,249	497,986
Goodwill	32,150	32,150
Other assets	27,002	26,259
Total assets	1,049,054	1,035,452
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	92,270	70,536
Accrued payroll and related expenses	17,528	12,130
Accrued insurance expenses	4,681	4,099
Accrued state, local and other taxes	4,746	3,094
Income taxes payable	3,805	4,929
Other accrued expenses	1,740	6,680
Total current liabilities	124,770	101,468
Long-term accrued insurance expenses	9,882	9,537
Long-term pension liabilities	33,637	32,864
Deferred income taxes	69,869	81,466
Other long-term liabilities	3,288	3,318
Total liabilities	241,446	228,653
Common stock	21,778	21,749
Capital in excess of par value
Retained earnings	803,770	803,152
Accumulated other comprehensive loss	(17,940)	(18,102)
Total stockholders' equity	807,608	806,799
Total liabilities and stockholders' equity	$ 1,049,054	$ 1,035,452