Condensed Consolidating Guarantor Financial Statements - Balance Sheets (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Jun. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 69,988		$ 93,699	$ 68,013		$ 74,216
Accounts receivable	662,372		653,484
Due from Related Parties, Current	187		1,691
Current assets held for sale	0		38,063
Inventories	49,232		101,665
Other Assets, Current	19,320		14,297
Assets, Current	801,099		902,899
Property, plant and equipment (net of accumulated depreciation of $570,720 and $444,842, respectively)	3,450,756		3,315,131
Equity method investments	277,021		285,281
Goodwill	257,302		257,302
Intangible Assets, Net (Excluding Goodwill)	373,439		398,643
Other noncurrent assets	138,158		132,600
Noncurrent assets held for sale	0		84,961
Assets	5,297,775		5,376,817
Current liabilities:
Accounts Payable	545,035		587,898
Due to Related Parties	1,294		6,971
Accrued liabilities	111,455		131,407
Current liabilities held for sale	0		23,847
Other current liabilities including deferred revenue and current portion of long-term debt	24,091		16,438
Liabilities, Current	681,875		766,561
Long-term debt, net	2,619,486		2,853,095
Deferred income taxes	52,897		46,585
Other Liabilities, Noncurrent	34,209		38,495
Noncurrent liabilities held for sale	0		13,716
Commitments and Contingencies
Preferred stock, $0.01 par value, $361,043 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	353,323		0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,555,985	$ 1,584,518	1,658,365	1,693,891	$ 1,405,399	1,445,965
Liabilities and Equity	5,297,775		5,376,817
Consolidation, Eliminations [Member]
Current assets:
Cash and cash equivalents	(2,704)		(8,630)	(3,995)		(4,582)
Accounts receivable	0		0
Due from Related Parties, Current	0		0
Current assets held for sale			0
Inventories	0		0
Other Assets, Current	0		0
Assets, Current	(2,704)		(8,630)
Property, plant and equipment (net of accumulated depreciation of $570,720 and $444,842, respectively)	0		0
Equity method investments	(4,242,592)		(4,910,292)
Goodwill	0		0
Intangible Assets, Net (Excluding Goodwill)	0		0
Other noncurrent assets	0		0
Noncurrent assets held for sale			0
Assets	(4,245,296)		(4,918,922)
Current liabilities:
Accounts Payable	0		0
Due to Related Parties	0		0
Accrued liabilities	4		(2)
Current liabilities held for sale			0
Other current liabilities including deferred revenue and current portion of long-term debt	0		0
Liabilities, Current	4		(2)
Long-term debt, net	(6,459)		(23,190)
Deferred income taxes	0		0
Other Liabilities, Noncurrent	0		0
Noncurrent liabilities held for sale			0
Commitments and Contingencies
Preferred stock, $0.01 par value, $361,043 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(4,238,841)		(4,895,730)
Liabilities and Equity	(4,245,296)		(4,918,922)
Reportable Legal Entities [Member] | Parent Company [Member]
Current assets:
Cash and cash equivalents	21,397		32,457	24,597		19,002
Accounts receivable	1		(9)
Due from Related Parties, Current	38		58
Current assets held for sale			0
Inventories	0		0
Other Assets, Current	5,672		6,671
Assets, Current	27,108		39,177
Property, plant and equipment (net of accumulated depreciation of $570,720 and $444,842, respectively)	7,014		8,086
Equity method investments	3,677,582		3,085,274
Goodwill	0		0
Intangible Assets, Net (Excluding Goodwill)	6		10
Other noncurrent assets	36,859		45,587
Noncurrent assets held for sale			0
Assets	3,748,569		3,178,134
Current liabilities:
Accounts Payable	535		646
Due to Related Parties	0		10
Accrued liabilities	25,827		38,747
Current liabilities held for sale			0
Other current liabilities including deferred revenue and current portion of long-term debt	3,431		1,922
Liabilities, Current	29,793		41,325
Long-term debt, net	1,806,432		1,474,491
Deferred income taxes	1,298		1,892
Other Liabilities, Noncurrent	1,738		2,061
Noncurrent liabilities held for sale			0
Commitments and Contingencies
Preferred stock, $0.01 par value, $361,043 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	353,323
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,555,985		1,658,365
Liabilities and Equity	3,748,569		3,178,134
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	0		0	0		0
Accounts receivable	545,033		562,967
Due from Related Parties, Current	3		1,421
Current assets held for sale			0
Inventories	49,232		101,665
Other Assets, Current	9,321		4,493
Assets, Current	603,589		670,546
Property, plant and equipment (net of accumulated depreciation of $570,720 and $444,842, respectively)	1,003,593		1,002,982
Equity method investments	842,031		2,110,299
Goodwill	0		0
Intangible Assets, Net (Excluding Goodwill)	121,633		127,783
Other noncurrent assets	3,262		3,097
Noncurrent assets held for sale			0
Assets	2,574,108		3,914,707
Current liabilities:
Accounts Payable	493,015		533,651
Due to Related Parties	1,294		6,961
Accrued liabilities	20,771		26,092
Current liabilities held for sale			0
Other current liabilities including deferred revenue and current portion of long-term debt	7,011		5,532
Liabilities, Current	522,091		572,236
Long-term debt, net	6,459		572,558
Deferred income taxes	0		0
Other Liabilities, Noncurrent	0		0
Noncurrent liabilities held for sale			0
Commitments and Contingencies
Preferred stock, $0.01 par value, $361,043 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,045,558		2,769,913
Liabilities and Equity	2,574,108		3,914,707
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	51,295		69,872	$ 47,411		$ 59,796
Accounts receivable	117,338		90,526
Due from Related Parties, Current	146		212
Current assets held for sale			38,063
Inventories	0		0
Other Assets, Current	4,327		3,133
Assets, Current	173,106		201,806
Property, plant and equipment (net of accumulated depreciation of $570,720 and $444,842, respectively)	2,440,149		2,304,063
Equity method investments	0		0
Goodwill	257,302		257,302
Intangible Assets, Net (Excluding Goodwill)	251,800		270,850
Other noncurrent assets	98,037		83,916
Noncurrent assets held for sale			84,961
Assets	3,220,394		3,202,898
Current liabilities:
Accounts Payable	51,485		53,601
Due to Related Parties	0		0
Accrued liabilities	64,853		66,570
Current liabilities held for sale			23,847
Other current liabilities including deferred revenue and current portion of long-term debt	13,649		8,984
Liabilities, Current	129,987		153,002
Long-term debt, net	813,054		829,236
Deferred income taxes	51,599		44,693
Other Liabilities, Noncurrent	32,471		36,434
Noncurrent liabilities held for sale			13,716
Commitments and Contingencies
Preferred stock, $0.01 par value, $361,043 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,193,283		2,125,817
Liabilities and Equity	$ 3,220,394		$ 3,202,898