Condensed Consolidating Financial Information - Balance Sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016	Mar. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 200,688	$ 264,093	$ 200,674	$ 254,530
Short-term investments	27,907	31,109
Accounts receivable, net	514,446	508,355
Inventory, net	109,461	103,595
Assets held for sale	77,118	76,668
Other current assets	193,036	172,019
Total current assets	1,122,656	1,155,839
Property, plant and equipment, net	6,218,699	6,267,583
Goodwill	166,999	166,917
Deferred tax assets	373,973	366,586
Other long-term assets	212,985	230,090
Total assets	8,095,312	8,187,015
Current liabilities:
Less: current portion	313	297
Trade accounts payable	241,332	264,578
Accrued liabilities	497,364	543,248
Income taxes payable	32,640	13,811
Total current liabilities	771,649	821,934
Long-term debt	3,661,665	3,578,335
Other long-term liabilities	467,248	522,456
Deferred income taxes	8,356	9,495
Total liabilities	4,908,918	4,932,220
Shareholders' equity	3,177,948	3,247,025
Noncontrolling interest	8,446	7,770
Total equity	3,186,394	3,254,795	3,916,197	4,293,868
Total liabilities and equity	8,095,312	8,187,015
Reportable Legal Entities | Parent Company
Current assets:
Cash and cash equivalents	8,579	1,148	1,570	873
Other current assets	57	50
Total current assets	8,636	1,198
Intercompany receivables	144,795	142,447
Investment in consolidated affiliates	3,044,185	3,170,254
Total assets	3,197,616	3,313,899
Current liabilities:
Trade accounts payable	113	205
Accrued liabilities	19,555	20,669
Total current liabilities	19,668	20,874
Intercompany payable		46,000
Total liabilities	19,668	66,874
Shareholders' equity	3,177,948	3,247,025
Total equity	3,177,948	3,247,025
Total liabilities and equity	3,197,616	3,313,899
Reportable Legal Entities | Guarantor Subsidiaries
Current assets:
Cash and cash equivalents	4	10,177	11	10
Other current assets	28,080	22,209
Total current assets	28,084	32,386
Investment in consolidated affiliates	4,779,879	4,830,572
Deferred tax assets	469,784	443,049
Other long-term assets	161	344
Total assets	5,277,908	5,306,351
Current liabilities:
Trade accounts payable	24	8
Accrued liabilities	27,386	65,246
Total current liabilities	27,410	65,254
Long-term debt	3,750,255	3,796,550
Other long-term liabilities	22,729	22,659
Intercompany payable	1,261,839	1,439,390
Total liabilities	5,062,233	5,323,853
Shareholders' equity	215,675	(17,502)
Total equity	215,675	(17,502)
Total liabilities and equity	5,277,908	5,306,351
Reportable Legal Entities | Other Subsidiaries (Non-Guarantors)
Current assets:
Cash and cash equivalents	192,105	252,768	$ 199,093	$ 253,647
Short-term investments	27,907	31,109
Accounts receivable, net	514,446	508,355
Inventory, net	109,461	103,595
Assets held for sale	77,118	76,668
Other current assets	164,899	149,760
Total current assets	1,085,936	1,122,255
Property, plant and equipment, net	6,218,699	6,267,583
Goodwill	166,999	166,917
Intercompany receivables	1,117,044	1,342,942
Investment in consolidated affiliates	1,151,049	1,083,948
Deferred tax assets	373,973	366,586
Other long-term assets	301,414	447,962
Total assets	10,415,114	10,798,193
Current liabilities:
Less: current portion	313	297
Trade accounts payable	241,195	264,365
Accrued liabilities	450,423	457,333
Income taxes payable	32,640	13,811
Total current liabilities	724,571	735,806
Other long-term liabilities	444,519	499,797
Deferred income taxes	478,140	452,544
Total liabilities	1,647,230	1,688,147
Shareholders' equity	8,759,438	9,102,276
Noncontrolling interest	8,446	7,770
Total equity	8,767,884	9,110,046
Total liabilities and equity	10,415,114	10,798,193
Consolidating Adjustments
Current assets:
Intercompany receivables	(1,261,839)	(1,485,389)
Investment in consolidated affiliates	(8,975,113)	(9,084,774)
Deferred tax assets	(469,784)	(443,049)
Other long-term assets	(88,590)	(218,216)
Total assets	(10,795,326)	(11,231,428)
Current liabilities:
Long-term debt	(88,590)	(218,215)
Deferred income taxes	(469,784)	(443,049)
Intercompany payable	(1,261,839)	(1,485,390)
Total liabilities	(1,820,213)	(2,146,654)
Shareholders' equity	(8,975,113)	(9,084,774)
Total equity	(8,975,113)	(9,084,774)
Total liabilities and equity	$ (10,795,326)	$ (11,231,428)