Condensed Consolidating Financial Information - Balance Sheet (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015	Jun. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 233,752	$ 254,530	$ 436,675	$ 501,149
Short-term investments	22,104	20,059
Assets held for sale	86,608	75,678	75,700
Accounts receivable, net	504,099	784,671
Inventory	151,753	153,824
Other current assets	192,927	187,135
Total current assets	1,191,243	1,475,897
Property, plant and equipment, net	6,765,257	7,027,802
Goodwill	167,275	166,659
Investment in unconsolidated affiliates	888	415,177
Other long-term assets	531,642	452,305
Total assets	8,656,305	9,537,840
Current liabilities:
Current portion of debt	175	6,508
Trade accounts payable	199,619	271,984
Accrued liabilities	650,019	686,613
Income taxes payable	18,362	41,394
Total current liabilities	868,175	1,006,499
Long-term debt	3,503,172	3,655,200
Other long-term liabilities	518,035	552,947
Deferred income taxes	44,225	29,326
Total liabilities	4,933,607	5,243,972
Shareholders' equity	3,715,850	4,282,710
Noncontrolling interest	6,848	11,158
Total equity	3,722,698	4,293,868	4,939,375	4,918,789
Total liabilities and equity	8,656,305	9,537,840
Reportable Legal Entities | Parent Company
Current assets:
Cash and cash equivalents	5,598	873	1,436	1,170
Other current assets	50	50
Total current assets	5,648	923
Intercompany receivables	146,459	139,366
Investment in consolidated affiliates	3,649,062	4,183,362
Total assets	3,801,169	4,323,651
Current liabilities:
Trade accounts payable	157	71
Accrued liabilities	20,162	370
Total current liabilities	20,319	441
Intercompany payable	65,000	40,500
Total liabilities	85,319	40,941
Shareholders' equity	3,715,850	4,282,710
Total equity	3,715,850	4,282,710
Total liabilities and equity	3,801,169	4,323,651
Reportable Legal Entities | Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	11	10	10	7
Other current assets	7,303	9,016
Total current assets	7,314	9,026
Intercompany receivables	11,000	11,000
Investment in consolidated affiliates	4,850,411	4,973,327
Deferred tax assets	404,434	366,818
Other long-term assets	362	12,907
Total assets	5,273,521	5,373,078
Current liabilities:
Trade accounts payable		3
Accrued liabilities	64,571	64,550
Total current liabilities	64,571	64,553
Long-term debt	3,725,182	3,723,138
Other long-term liabilities	22,554	35,086
Intercompany payable	1,467,864	1,370,176
Total liabilities	5,280,171	5,192,953
Shareholders' equity	(6,650)	180,125
Total equity	(6,650)	180,125
Total liabilities and equity	5,273,521	5,373,078
Reportable Legal Entities | Other Subsidiaries (Non-Guarantors)
Current assets:
Cash and cash equivalents	228,143	253,647	$ 435,229	$ 499,972
Short-term investments	22,104	20,059
Assets held for sale	86,608	75,678
Accounts receivable, net	504,099	784,671
Inventory	151,753	153,824
Other current assets	185,574	178,069
Total current assets	1,178,281	1,465,948
Property, plant and equipment, net	6,765,257	7,027,802
Goodwill	167,275	166,659
Intercompany receivables	1,375,405	1,260,310
Investment in consolidated affiliates	1,092,713	1,284,225
Investment in unconsolidated affiliates	888	415,177
Other long-term assets	753,290	507,336
Total assets	11,333,109	12,127,457
Current liabilities:
Current portion of debt	175	6,508
Trade accounts payable	199,462	271,910
Accrued liabilities	565,286	621,693
Income taxes payable	18,362	41,394
Total current liabilities	783,285	941,505
Other long-term liabilities	495,481	517,861
Deferred income taxes	448,659	396,144
Total liabilities	1,727,425	1,855,510
Shareholders' equity	9,598,836	10,260,789
Noncontrolling interest	6,848	11,158
Total equity	9,605,684	10,271,947
Total liabilities and equity	11,333,109	12,127,457
Consolidating Adjustments
Current assets:
Intercompany receivables	(1,532,864)	(1,410,676)
Investment in consolidated affiliates	(9,592,186)	(10,440,914)
Deferred tax assets	(404,434)	(366,818)
Other long-term assets	(222,010)	(67,938)
Total assets	(11,751,494)	(12,286,346)
Current liabilities:
Long-term debt	(222,010)	(67,938)
Deferred income taxes	(404,434)	(366,818)
Intercompany payable	(1,532,864)	(1,410,676)
Total liabilities	(2,159,308)	(1,845,432)
Shareholders' equity	(9,592,186)	(10,440,914)
Total equity	(9,592,186)	(10,440,914)
Total liabilities and equity	$ (11,751,494)	$ (12,286,346)