Condensed Consolidated Balance Sheets (Unaudited) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 1,783,518	$ 1,077,429
Accounts receivable (less accumulated provision for doubtful accounts: $4,775 at March 31, 2015 and $5,311 at December 31, 2014)	237,067	306,085
Derivative instruments, at fair value	458,760	458,460
Prepaid expenses and other	43,140	62,349
Total current assets	2,522,485	1,904,323
Equity in nonconsolidated investments	46,084	0
Property, plant and equipment	14,140,428	13,608,151
Less: accumulated depreciation and depletion	3,720,366	3,531,337
Net property, plant and equipment	10,420,062	10,076,814
Other assets	77,687	83,763
Total assets	13,066,318	12,064,900
Current liabilities:
Current portion of long-term debt	167,243	166,011
Short-term loans	299,000	0
Accounts payable	326,133	444,077
Derivative instruments, at fair value	55,115	22,942
Other current liabilities	208,084	200,449
Total current liabilities	1,055,575	833,479
Long-term debt	2,818,200	2,822,889
Deferred income taxes	1,765,641	1,750,870
Other liabilities and credits	286,737	284,599
Total liabilities	5,926,153	5,691,837
Stockholders’ equity:
Common stock, no par value, authorized 320,000 shares, shares issued: 175,384 at March 31, 2015 and 175,384 at December 31, 2014	1,994,659	1,895,632
Treasury stock, shares at cost: 23,038 at March 31, 2015 and 23,788 at December 31, 2014	(415,875)	(429,440)
Retained earnings	3,085,994	2,917,129
Accumulated other comprehensive income	158,981	199,494
Total common stockholders’ equity	4,823,759	4,582,815
Noncontrolling interests in consolidated subsidiaries	2,316,406	1,790,248
Total equity	7,140,165	6,373,063
Total liabilities and equity	$ 13,066,318	$ 12,064,900