Unaudited Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2020	Dec. 31, 2019
ASSETS
Cash and cash equivalents	$ 95,546	$ 122,892
Trade accounts receivable, net	20,335	15,444
Accounts receivable from affiliates	4,715	6,411
Inventories	35,732	40,465
Refundable federal income taxes	15,286	8,928
Other current assets	19,089	6,528
Total current assets	190,703	200,668
Property, plant and equipment, net	143,208	138,061
Intangibles, net	36,333	37,902
Investments in unconsolidated subsidiaries	25,337	24,611
Operating lease right-of-use assets	10,748	11,398
Other non-current assets	36,625	32,133
Total assets	442,954	444,773
LIABILITIES AND EQUITY
Accounts payable	9,822	9,374
Accounts payable to affiliates	1,907	577
Revolving credit agreements	5,000	7,000
Current maturities of long-term debt	941	795
Asset retirement obligations	2,285	2,285
Accrued payroll	11,405	19,583
Deferred compensation	0	13,465
Deferred revenue	1,226	1,908
Other current liabilities	6,675	6,979
Total current liabilities	39,261	61,966
Long-term debt	22,482	17,148
Operating lease liabilities	11,782	12,448
Asset retirement obligations	35,421	34,574
Pension and other postretirement obligations	7,883	8,807
Deferred income taxes	18,345	12,338
Other long-term liabilities	8,509	8,100
Total liabilities	143,683	155,381
Common stock:
Capital in excess of par value	8,942	8,911
Retained earnings	294,378	284,852
Accumulated other comprehensive loss	(11,081)	(11,337)
Total stockholders' equity	299,271	289,392
Total liabilities and equity	442,954	444,773
Class A Common Stock
Common stock:
Common stock	5,463	5,397
Class B Common Stock
Common stock:
Common stock	$ 1,569	$ 1,569