Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017
Current Assets:
Cash and cash equivalents	$ 284,355	$ 521,375
Short-term investments	41,461	44,491
Accounts receivable, net of allowance of $6,217 and $5,721, respectively	565,202	477,074
Inventories of materials and supplies, net	158,134	137,204
Prepaid expenses and other	66,398	55,123
Total current assets	1,115,550	1,235,267
Investments	98,696	84,026
Property, plant and equipment, net	4,857,382	5,001,051
Noncurrent Assets:
Goodwill	64,777	51,705
Intangible assets, net	73,207	50,785
Other assets	5,255	17,154
Total noncurrent assets	143,239	119,644
Total Assets	6,214,867	6,439,988
Current Liabilities:
Accounts payable	132,664	135,628
Accrued liabilities	244,504	208,757
Total current liabilities	377,168	344,385
Noncurrent Liabilities:
Long-term debt	493,968	492,902
Deferred income taxes	853,136	1,332,689
Other	93,606	101,409
Total noncurrent liabilities	1,454,964	1,931,012
Commitments and Contingencies (Note 15)
Shareholders' Equity:
Common stock, $.10 par value, 160,000,000 shares authorized,112,008,961 and 111,956,875 shares issued as of September 30, 2018 and 2017, respectively, and 108,993,718 and 108,604,047 shares outstanding as of September 30, 2018 and 2017, respectively	11,201	11,196
Preferred stock, no par value, 1,000,000 shares authorized, no shares issued
Additional paid-in capital	500,393	487,248
Retained earnings	4,027,779	3,855,686
Accumulated other comprehensive income	16,550	2,300
Treasury stock, at cost, 3,015,243 shares and 3,352,828 shares as of September 30, 2018 and 2017, respectively	(173,188)	(191,839)
Total shareholders' equity	4,382,735	4,164,591
Total liabilities and shareholders' equity	$ 6,214,867	$ 6,439,988