Condensed Consolidating Financial Information - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 200,674	$ 254,530	$ 586,001	$ 501,149
Short-term investments	20,827	20,059
Assets held for sale	80,100	75,678
Accounts receivable, net	594,506	784,671
Inventory	153,837	153,824
Other current assets	209,443	187,135
Total current assets	1,259,387	1,475,897
Property, plant and equipment, net	6,942,315	7,027,802
Goodwill	167,217	166,659
Investment in unconsolidated affiliates	94,657	415,177
Other long-term assets	486,755	452,305
Total assets	8,950,331	9,537,840
Current liabilities:
Current portion of debt	5,880	6,508
Trade accounts payable	250,078	271,984
Accrued liabilities	572,025	686,613
Income taxes payable	43,285	41,394
Total current liabilities	871,268	1,006,499
Long-term debt	3,584,402	3,655,200
Other long-term liabilities	565,086	552,947
Deferred income taxes	13,378	29,326
Total liabilities	5,034,134	5,243,972
Shareholders' equity	3,904,320	4,282,710
Noncontrolling interest	11,877	11,158
Total equity	3,916,197	4,293,868	4,967,762	4,918,789
Total liabilities and equity	8,950,331	9,537,840
Reportable Legal Entities | Parent Company
Current assets:
Cash and cash equivalents	1,570	873	4,370	1,170
Other current assets	50	50
Total current assets	1,620	923
Intercompany receivables	142,423	139,366
Investment in consolidated affiliates	3,823,216	4,183,362
Total assets	3,967,259	4,323,651
Current liabilities:
Trade accounts payable	127	71
Accrued liabilities	312	370
Total current liabilities	439	441
Intercompany payable	62,500	40,500
Total liabilities	62,939	40,941
Shareholders' equity	3,904,320	4,282,710
Total equity	3,904,320	4,282,710
Total liabilities and equity	3,967,259	4,323,651
Reportable Legal Entities | Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	11	10	18	7
Other current assets	8,471	9,016
Total current assets	8,482	9,026
Intercompany receivables	11,000	11,000
Investment in consolidated affiliates	4,867,299	4,973,327
Deferred tax assets	385,543	366,818
Other long-term assets	435	12,907
Total assets	5,272,759	5,373,078
Current liabilities:
Trade accounts payable	25	3
Accrued liabilities	18,494	64,550
Total current liabilities	18,519	64,553
Long-term debt	3,806,412	3,723,138
Other long-term liabilities	22,501	35,086
Intercompany payable	1,383,019	1,370,176
Total liabilities	5,230,451	5,192,953
Shareholders' equity	42,308	180,125
Total equity	42,308	180,125
Total liabilities and equity	5,272,759	5,373,078
Reportable Legal Entities | Other Subsidiaries (Non-Guarantors)
Current assets:
Cash and cash equivalents	199,093	253,647	$ 581,613	$ 499,972
Short-term investments	20,827	20,059
Assets held for sale	80,100	75,678
Accounts receivable, net	594,506	784,671
Inventory	153,837	153,824
Other current assets	200,922	178,069
Total current assets	1,249,285	1,465,948
Property, plant and equipment, net	6,942,315	7,027,802
Goodwill	167,217	166,659
Intercompany receivables	1,292,096	1,260,310
Investment in consolidated affiliates	1,146,408	1,284,225
Investment in unconsolidated affiliates	94,657	415,177
Other long-term assets	708,330	507,336
Total assets	11,600,308	12,127,457
Current liabilities:
Current portion of debt	5,880	6,508
Trade accounts payable	249,926	271,910
Accrued liabilities	553,219	621,693
Income taxes payable	43,285	41,394
Total current liabilities	852,310	941,505
Other long-term liabilities	542,585	517,861
Deferred income taxes	398,921	396,144
Total liabilities	1,793,816	1,855,510
Shareholders' equity	9,794,615	10,260,789
Noncontrolling interest	11,877	11,158
Total equity	9,806,492	10,271,947
Total liabilities and equity	11,600,308	12,127,457
Consolidating Adjustments
Current assets:
Intercompany receivables	(1,445,519)	(1,410,676)
Investment in consolidated affiliates	(9,836,923)	(10,440,914)
Deferred tax assets	(385,543)	(366,818)
Other long-term assets	(222,010)	(67,938)
Total assets	(11,889,995)	(12,286,346)
Current liabilities:
Long-term debt	(222,010)	(67,938)
Deferred income taxes	(385,543)	(366,818)
Intercompany payable	(1,445,519)	(1,410,676)
Total liabilities	(2,053,072)	(1,845,432)
Shareholders' equity	(9,836,923)	(10,440,914)
Total equity	(9,836,923)	(10,440,914)
Total liabilities and equity	$ (11,889,995)	$ (12,286,346)