CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
ASSETS
Cash and cash equivalents	$ 94,175	$ 91,050
Accounts receivable, net of allowance for doubtful accounts of $5,022 in 2018 and $4,471 in 2017	376,815	377,853
Inventories	126,504	114,866
Income taxes receivable	21,258	40,243
Prepaid expenses	6,382	8,992
Other current assets	5,924	7,131
Total current assets	631,058	640,135
Property, plant and equipment, less accumulated depreciation of $1,693,141 in 2018 and $1,659,311 in 2017	523,330	443,928
Goodwill	32,150	32,150
Other assets	32,110	31,011
Total assets	1,218,648	1,147,224
LIABILITIES AND STOCKHOLDERS' EQUITY
Accounts payable	138,971	103,462
Accrued payroll and related expenses	24,061	23,577
Accrued insurance expenses	5,592	5,299
Accrued state, local and other taxes	5,904	8,655
Income taxes payable	7,566	3,224
Other accrued expenses	1,302	1,143
Total current liabilities	183,396	145,360
Long-term accrued insurance expenses	10,816	10,376
Long-term pension liabilities	30,833	35,635
Deferred income taxes	44,715	39,437
Other long-term liabilities	3,901	4,719
Total liabilities	273,661	235,527
Common stock	21,483	21,654
Capital in excess of par value	0	0
Retained earnings	940,308	906,745
Accumulated other comprehensive loss	(16,804)	(16,702)
Total stockholders' equity	944,987	911,697
Total liabilities and stockholders' equity	$ 1,218,648	$ 1,147,224