Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017
Current Assets:
Cash and cash equivalents	$ 53,961	$ 1,446,364	$ 35,219
Accounts receivable, net	644,835	487,240	582,532
Inventories, net	651,295	600,591	576,429
Other current assets	104,717	96,965	83,809
Total Current Assets	1,454,808	2,631,160	1,277,989
Property, plant and equipment	8,183,412	6,498,067	6,375,813
Allowances for depreciation, depletion and amortization	(3,080,017)	(2,905,254)	(2,854,236)
Net property, plant and equipment	5,103,395	3,592,813	3,521,577
Goodwill	2,399,434	2,160,290	2,160,060
Operating permits, net	434,177	439,116	440,846
Other intangibles, net	74,799	67,233	63,740
Other noncurrent assets	121,558	101,899	102,573
Total Assets	9,588,171	8,992,511	7,566,785
Current Liabilities:
Bank overdraft			1,047
Accounts payable	191,381	183,638	163,597
Accrued salaries, benefits and payroll taxes	45,234	44,255	37,885
Pension and postretirement benefits	9,292	13,652	12,073
Accrued insurance and other taxes	69,513	64,958	70,323
Current maturities of long-term debt and short-term facilities	380,041	299,909	80,038
Accrued interest	31,708	19,825	28,082
Other current liabilities	45,517	67,979	75,458
Total Current Liabilities	772,686	694,216	468,503
Long-term debt	2,829,657	2,727,294	1,642,502
Pension, postretirement and postemployment benefits	108,454	244,043	230,212
Deferred income taxes, net	692,881	410,723	662,982
Other noncurrent liabilities	242,165	233,758	228,604
Total Liabilities	4,645,843	4,310,034	3,232,803
Equity:
Common stock, par value $0.01 per share	626	628	627
Preferred stock, par value $0.01 per share
Additional paid-in capital	3,391,133	3,368,007	3,362,744
Accumulated other comprehensive loss	(121,491)	(129,104)	(122,928)
Retained earnings	1,669,126	1,440,069	1,090,778
Total Shareholders' Equity	4,939,394	4,679,600	4,331,221
Noncontrolling interests	2,934	2,877	2,761
Total Equity	4,942,328	4,682,477	4,333,982
Total Liabilities and Equity	$ 9,588,171	$ 8,992,511	$ 7,566,785