Condensed Consolidating Guarantor Financial Statements - Balance Sheets (Details) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 56,535	$ 74,216	$ 255,780	$ 58,096
Accounts receivable, net	381,345	418,339
Due from Related Parties, Current	8,650	25,455
Inventories	80,446	99,234
Other Assets, Current	16,150	18,630
Assets, Current	543,126	635,874
Property, plant and equipment (net of accumulated depreciation of $443,872 and $393,635, respectively)	1,948,787	1,762,072
Equity method investments	430,514	434,289
Goodwill	34,802	34,230
Intangible Assets, Net (Excluding Goodwill)	145,639	150,978
Other noncurrent assets	63,350	57,529
Assets	3,166,218	3,074,972
Current liabilities:
Accounts Payable	326,810	367,307
Due to Related Parties	3,508	26,508
Accrued liabilities	113,783	81,104
Other current liabilities including deferred revenue and current portion of long-term debt	11,373	13,436
Liabilities, Current	455,474	488,355
Long-term debt, net	1,215,244	1,050,918
Deferred income taxes	63,323	64,501
Other Liabilities, Noncurrent	26,778	25,233
Commitments and Contingencies
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,405,399	1,445,965
Liabilities and Equity	3,166,218	3,074,972
Consolidation, Eliminations [Member]
Current assets:
Cash and cash equivalents	(2,389)	(4,582)	0	(1,564)
Accounts receivable, net	(8)	0
Due from Related Parties, Current	0	0
Inventories	0	0
Other Assets, Current	8	(3)
Assets, Current	(2,389)	(4,585)
Property, plant and equipment (net of accumulated depreciation of $443,872 and $393,635, respectively)	0	0
Equity method investments	(3,215,371)	(2,960,525)
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	0	0
Other noncurrent assets	0	0
Assets	(3,217,760)	(2,965,110)
Current liabilities:
Accounts Payable	0	0
Due to Related Parties	0	0
Accrued liabilities	3	0
Other current liabilities including deferred revenue and current portion of long-term debt	0	0
Liabilities, Current	3	0
Long-term debt, net	(22,947)	(22,617)
Deferred income taxes	0	0
Other Liabilities, Noncurrent	0	0
Commitments and Contingencies
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(3,194,816)	(2,942,493)
Liabilities and Equity	(3,217,760)	(2,965,110)
Reportable Legal Entities [Member] | Parent Company [Member]
Current assets:
Cash and cash equivalents	9,218	19,002	187,987	4,559
Accounts receivable, net	0	0
Due from Related Parties, Current	872	27
Inventories	0	0
Other Assets, Current	6,112	8,986
Assets, Current	16,202	28,015
Property, plant and equipment (net of accumulated depreciation of $443,872 and $393,635, respectively)	7,580	5,621
Equity method investments	2,598,141	2,454,118
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	13	15
Other noncurrent assets	44,599	54,155
Assets	2,666,535	2,541,924
Current liabilities:
Accounts Payable	884	674
Due to Related Parties	0	0
Accrued liabilities	31,977	25,078
Other current liabilities including deferred revenue and current portion of long-term debt	1,485	889
Liabilities, Current	34,346	26,641
Long-term debt, net	1,215,233	1,050,893
Deferred income taxes	9,615	16,119
Other Liabilities, Noncurrent	1,942	2,306
Commitments and Contingencies
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,405,399	1,445,965
Liabilities and Equity	2,666,535	2,541,924
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	0	0	7,087	9,058
Accounts receivable, net	308,737	361,160
Due from Related Parties, Current	7,578	25,244
Inventories	70,050	89,638
Other Assets, Current	5,497	5,760
Assets, Current	391,862	481,802
Property, plant and equipment (net of accumulated depreciation of $443,872 and $393,635, respectively)	971,828	970,079
Equity method investments	1,047,744	940,696
Goodwill	26,628	26,628
Intangible Assets, Net (Excluding Goodwill)	144,503	149,669
Other noncurrent assets	1,934	2,080
Assets	2,584,499	2,570,954
Current liabilities:
Accounts Payable	292,924	348,297
Due to Related Parties	3,508	26,508
Accrued liabilities	30,162	23,423
Other current liabilities including deferred revenue and current portion of long-term debt	4,284	5,108
Liabilities, Current	330,878	403,336
Long-term debt, net	6,458	6,142
Deferred income taxes	0	0
Other Liabilities, Noncurrent	0	0
Commitments and Contingencies
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,247,163	2,161,476
Liabilities and Equity	2,584,499	2,570,954
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	49,706	59,796	$ 60,706	$ 46,043
Accounts receivable, net	72,616	57,179
Due from Related Parties, Current	200	184
Inventories	10,396	9,596
Other Assets, Current	4,533	3,887
Assets, Current	137,451	130,642
Property, plant and equipment (net of accumulated depreciation of $443,872 and $393,635, respectively)	969,379	786,372
Equity method investments	0	0
Goodwill	8,174	7,602
Intangible Assets, Net (Excluding Goodwill)	1,123	1,294
Other noncurrent assets	16,817	1,294
Assets	1,132,944	927,204
Current liabilities:
Accounts Payable	33,002	18,336
Due to Related Parties	0	0
Accrued liabilities	51,641	32,603
Other current liabilities including deferred revenue and current portion of long-term debt	5,604	7,439
Liabilities, Current	90,247	58,378
Long-term debt, net	16,500	16,500
Deferred income taxes	53,708	48,382
Other Liabilities, Noncurrent	24,836	22,927
Commitments and Contingencies
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	947,653	781,017
Liabilities and Equity	$ 1,132,944	$ 927,204