CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Assets
Cash and cash equivalents	$ 857,555	$ 1,197,068	$ 816,765
Restricted cash	110,851	945	434
Accounts and notes receivable
Accounts and notes receivable, gross	689,591	558,848	699,320
Allowance for doubtful accounts	(2,739)	(2,551)	(3,460)
Accounts and notes receivable, net	686,852	556,297	695,860
Inventories
Finished products	373,677	378,389	383,483
Raw materials	37,967	33,780	33,178
Products in process	5,099	4,555	5,116
Operating supplies and other	33,900	31,861	29,703
Inventories	450,643	448,585	451,480
Other current assets	94,524	74,270	65,571
Total current assets	2,200,425	2,277,165	2,030,110
Investments and long-term receivables	34,264	34,301	43,849
Property, plant & equipment
Property, plant & equipment, cost	9,094,689	9,102,086	8,921,990
Allowances for depreciation, depletion & amortization	(4,729,456)	(4,676,087)	(4,538,980)
Property, plant & equipment, net	4,365,233	4,425,999	4,383,010
Operating lease right-of-use assets, net	464,765	423,128	426,618
Goodwill	3,172,112	3,172,112	3,172,112
Other intangible assets, net	1,103,079	1,123,544	1,114,592
Other noncurrent assets	231,149	230,656	228,433
Total assets	11,571,027	11,686,905	11,398,724
Liabilities
Current maturities of long-term debt	15,436	515,435	500,026
Trade payables and accruals	300,109	273,080	278,102
Other current liabilities	283,700	259,368	260,621
Total current liabilities	599,245	1,047,883	1,038,749
Long-term debt	2,769,892	2,772,240	2,785,646
Deferred income taxes, net	748,279	706,050	671,097
Deferred revenue	170,160	174,045	177,534
Noncurrent operating lease liabilities	443,128	399,582	405,578
Other noncurrent liabilities	547,210	559,775	555,969
Total liabilities	5,277,914	5,659,575	5,634,573
Other commitments and contingencies (Note 8)
Equity
Common stock, $1 par value, Authorized 480,000 shares, Outstanding 132,678, 132,516 and 132,446 shares, respectively	132,678	132,516	132,446
Capital in excess of par value	2,806,693	2,802,012	2,789,801
Retained earnings	3,531,861	3,274,107	3,049,943
Accumulated other comprehensive loss	(178,119)	(181,305)	(208,039)
Total equity	6,293,113	6,027,330	5,764,151
Total liabilities and equity	$ 11,571,027	$ 11,686,905	$ 11,398,724