CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
ASSETS
Cash and cash equivalents	$ 85,421	$ 84,496
Accounts receivable, net of allowance for credit losses of $5,717 in 2021 and $4,815 in 2020	186,891	161,771
Inventories	80,165	82,918
Income taxes receivable	82,612	82,943
Prepaid expenses	8,027	9,124
Assets held for sale	4,032	4,032
Other current assets	2,493	3,075
Total current assets	449,641	428,359
Property, plant and equipment, less accumulated depreciation of $788,922 in 2021 and $790,712 in 2020	257,309	264,411
Operating lease right-of-use assets	25,400	27,270
Goodwill	32,150	32,150
Other assets	35,573	38,315
Total assets	800,073	790,505
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	60,649	41,080
Accrued payroll and related expenses	23,074	18,428
Accrued insurance expenses	4,443	5,489
Accrued state, local and other taxes	4,539	2,788
Income taxes payable	1,302	1,115
Current portion of operating lease liabilities	8,594	9,192
Other accrued expenses	946	1,473
Total current liabilities	103,547	79,565
Long-term accrued insurance expenses	10,543	11,822
Long-term pension liabilities	31,088	33,080
Deferred income taxes	12,631	13,332
Long-term operating lease liabilities	19,088	21,090
Other long-term liabilities		49
Total liabilities	176,897	158,938
STOCKHOLDER'S EQUITY
Common stock	21,574	21,495
Capital in excess of par value	0	0
Retained earnings	619,019	627,778
Accumulated other comprehensive loss	(17,417)	(17,706)
Total stockholders' equity	623,176	631,567
Total liabilities and stockholders' equity	$ 800,073	$ 790,505