Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016
Current Assets:
Cash and cash equivalents	$ 55,418	$ 50,038	$ 27,242
Accounts receivable, net	479,215	457,910	448,048
Inventories, net	537,000	521,624	485,367
Other current assets	51,609	56,813	37,658
Total Current Assets	1,123,242	1,086,385	998,315
Property, plant and equipment	6,211,813	6,115,530	5,778,368
Allowances for depreciation, depletion and amortization	(2,744,168)	(2,692,135)	(2,515,387)
Net property, plant and equipment	3,467,645	3,423,395	3,262,981
Goodwill	2,159,398	2,159,337	2,135,295
Operating permits, net	440,411	442,202	444,148
Other intangibles, net	67,318	69,110	75,267
Other noncurrent assets	135,777	120,476	142,281
Total Assets	7,393,791	7,300,905	7,058,287
Current Liabilities:
Accounts payable	188,399	178,598	174,398
Accrued salaries, benefits and payroll taxes	22,760	47,428	17,052
Pension and postretirement benefits	8,136	9,293	9,169
Accrued insurance and other taxes	49,535	60,093	52,501
Current maturities of long-term debt and short-term facilities	290,048	180,036	177,430
Accrued interest	23,649	16,837	23,004
Other current liabilities	49,031	54,303	38,577
Total Current Liabilities	631,558	546,588	492,131
Long-term debt	1,556,246	1,506,153	1,575,327
Pension, postretirement and postemployment benefits	252,568	248,086	226,924
Deferred income taxes, net	667,160	663,019	620,569
Other noncurrent liabilities	210,305	194,469	197,700
Total Liabilities	3,317,837	3,158,315	3,112,651
Equity:
Common stock, par value $0.01 per share	626	630	633
Preferred stock, par value $0.01 per share
Additional paid-in capital	3,349,813	3,334,461	3,302,258
Accumulated other comprehensive loss	(128,425)	(130,687)	(103,833)
Retained earnings	851,354	935,574	743,593
Total Shareholders' Equity	4,073,368	4,139,978	3,942,651
Noncontrolling interests	2,586	2,612	2,985
Total Equity	4,075,954	4,142,590	3,945,636
Total Liabilities and Equity	$ 7,393,791	$ 7,300,905	$ 7,058,287