Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Current assets:
Cash and cash equivalents	$ 1,274,265	$ 845,641
Restricted cash	342,744
Accounts receivable (less accumulated provision for doubtful accounts: $6,139 at June 30, 2014 and $5,171 at December 31, 2013)	235,306	235,781
Inventory	13,389	19,656
Derivative instruments, at fair value	66,408	107,647
Prepaid expenses and other	32,065	46,700
Total current assets	1,964,177	1,255,425
Equity in nonconsolidated investments		128,983
Property, plant and equipment	12,372,135	11,062,136
Less: accumulated depreciation and depletion	3,024,600	2,728,374
Net property, plant and equipment	9,347,535	8,333,762
Other assets	74,224	73,883
Total assets	11,385,936	9,792,053
Current liabilities:
Current portion of long-term debt	11,086	11,162
Short-term loans	330,000
Accounts payable	381,280	330,329
Derivative instruments, at fair value	58,116	29,651
Other current liabilities	168,483	152,268
Total current liabilities	948,965	523,410
Long-term debt	2,486,533	2,490,354
Deferred income taxes	1,654,506	1,655,765
Other liabilities and credits	265,999	258,396
Total liabilities	5,356,003	4,927,925
Stockholders' equity:
Common stock, no par value, authorized 320,000 shares, shares issued: 175,384 at June 30, 2014 and 175,684 at December 31, 2013	1,861,468	1,869,843
Treasury stock, shares at cost: 23,882 at June 30, 2014 and 24,800 at December 31, 2013	(431,149)	(447,738)
Retained earnings	2,842,384	2,567,980
Accumulated other comprehensive income	3,889	44,703
Total common stockholders' equity	4,276,592	4,034,788
Noncontrolling interests in consolidated subsidiaries	1,753,341	829,340
Total equity	6,029,933	4,864,128
Total liabilities and equity	$ 11,385,936	$ 9,792,053