Condensed Consolidating Guarantor Financial Statements - Balance Sheets (Details) - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017	Mar. 31, 2017	Dec. 31, 2016
Current assets:
Cash and cash equivalents	$ 285,498	$ 93,699	$ 65,856	$ 74,216
Accounts receivable	535,705	653,484
Due from Related Parties, Current	937	1,691
Current assets held for sale	2,501	38,063
Inventories	81,542	101,665
Other Assets, Current	17,341	14,297
Assets, Current	923,524	902,899
Property, plant and equipment (net of accumulated depreciation of $483,904 and $444,842, respectively)	3,380,574	3,315,131
Equity method investments	279,054	285,281
Goodwill	257,302	257,302
Intangible Assets, Net (Excluding Goodwill)	390,242	398,643
Other noncurrent assets	142,845	132,600
Noncurrent assets held for sale	65,784	84,961
Assets	5,439,325	5,376,817
Current liabilities:
Accounts Payable	492,507	587,898
Due to Related Parties	2,321	6,971
Accrued liabilities	100,373	131,407
Current liabilities held for sale	2,434	23,847
Other current liabilities including deferred revenue and current portion of long-term debt	33,023	16,438
Liabilities, Current	630,658	766,561
Long-term debt, net	2,733,957	2,853,095
Deferred income taxes	60,551	46,585
Other Liabilities, Noncurrent	37,384	38,495
Noncurrent liabilities held for sale	14,258	13,716
Commitments and Contingencies
Preferred stock, $0.01 par value, $350,000 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	342,354	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,620,163	1,658,365
Liabilities and Equity	5,439,325	5,376,817
Consolidation, Eliminations [Member]
Current assets:
Cash and cash equivalents	(4,863)	(8,630)	(4,445)	(4,582)
Accounts receivable	0	0
Due from Related Parties, Current	0	0
Current assets held for sale	0	0
Inventories	0	0
Other Assets, Current	0	0
Assets, Current	(4,863)	(8,630)
Property, plant and equipment (net of accumulated depreciation of $483,904 and $444,842, respectively)	0	0
Equity method investments	(3,663,985)	(3,764,923)
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	0	0
Other noncurrent assets	0	0
Noncurrent assets held for sale	0	0
Assets	(3,668,848)	(3,773,553)
Current liabilities:
Accounts Payable	0	0
Due to Related Parties	0	0
Accrued liabilities	0	(2)
Current liabilities held for sale	0	0
Other current liabilities including deferred revenue and current portion of long-term debt	0	0
Liabilities, Current	0	(2)
Long-term debt, net	(23,447)	(23,190)
Deferred income taxes	0	0
Other Liabilities, Noncurrent	0	0
Noncurrent liabilities held for sale	0	0
Commitments and Contingencies
Preferred stock, $0.01 par value, $350,000 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	(3,645,401)	(3,750,361)
Liabilities and Equity	(3,668,848)	(3,773,553)
Reportable Legal Entities [Member] | Parent Company [Member]
Current assets:
Cash and cash equivalents	233,282	32,457	8,214	19,002
Accounts receivable	57	(9)
Due from Related Parties, Current	177	58
Current assets held for sale	0	0
Inventories	0	0
Other Assets, Current	4,407	6,671
Assets, Current	237,923	39,177
Property, plant and equipment (net of accumulated depreciation of $483,904 and $444,842, respectively)	7,774	8,086
Equity method investments	3,069,175	3,085,274
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	9	10
Other noncurrent assets	47,943	45,587
Noncurrent assets held for sale	0	0
Assets	3,362,824	3,178,134
Current liabilities:
Accounts Payable	1,263	646
Due to Related Parties	2	10
Accrued liabilities	24,385	38,747
Current liabilities held for sale	0	0
Other current liabilities including deferred revenue and current portion of long-term debt	14,495	1,922
Liabilities, Current	40,145	41,325
Long-term debt, net	1,344,164	1,474,491
Deferred income taxes	13,704	1,892
Other Liabilities, Noncurrent	2,294	2,061
Noncurrent liabilities held for sale	0	0
Commitments and Contingencies
Preferred stock, $0.01 par value, $350,000 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	342,354
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,620,163	1,658,365
Liabilities and Equity	3,362,824	3,178,134
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Accounts receivable	456,180	562,967
Due from Related Parties, Current	84	1,421
Current assets held for sale	0	0
Inventories	81,542	101,665
Other Assets, Current	6,423	4,493
Assets, Current	544,229	670,546
Property, plant and equipment (net of accumulated depreciation of $483,904 and $444,842, respectively)	1,013,976	1,002,982
Equity method investments	873,864	964,930
Goodwill	0	0
Intangible Assets, Net (Excluding Goodwill)	125,733	127,783
Other noncurrent assets	2,866	3,097
Noncurrent assets held for sale	0	0
Assets	2,560,668	2,769,338
Current liabilities:
Accounts Payable	436,443	533,651
Due to Related Parties	2,319	6,961
Accrued liabilities	22,877	26,275
Current liabilities held for sale	0	0
Other current liabilities including deferred revenue and current portion of long-term debt	7,562	5,532
Liabilities, Current	469,201	572,419
Long-term debt, net	6,947	6,690
Deferred income taxes	0	0
Other Liabilities, Noncurrent	0	0
Noncurrent liabilities held for sale	0	0
Commitments and Contingencies
Preferred stock, $0.01 par value, $350,000 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	2,084,520	2,190,229
Liabilities and Equity	2,560,668	2,769,338
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	57,079	69,872	$ 62,087	$ 59,796
Accounts receivable	79,468	90,526
Due from Related Parties, Current	676	212
Current assets held for sale	2,501	38,063
Inventories	0	0
Other Assets, Current	6,511	3,133
Assets, Current	146,235	201,806
Property, plant and equipment (net of accumulated depreciation of $483,904 and $444,842, respectively)	2,358,824	2,304,063
Equity method investments	0	0
Goodwill	257,302	257,302
Intangible Assets, Net (Excluding Goodwill)	264,500	270,850
Other noncurrent assets	92,036	83,916
Noncurrent assets held for sale	65,784	84,961
Assets	3,184,681	3,202,898
Current liabilities:
Accounts Payable	54,801	53,601
Due to Related Parties	0	0
Accrued liabilities	53,111	66,387
Current liabilities held for sale	2,434	23,847
Other current liabilities including deferred revenue and current portion of long-term debt	10,966	8,984
Liabilities, Current	121,312	152,819
Long-term debt, net	1,406,293	1,395,104
Deferred income taxes	46,847	44,693
Other Liabilities, Noncurrent	35,090	36,434
Noncurrent liabilities held for sale	14,258	13,716
Commitments and Contingencies
Preferred stock, $0.01 par value, $350,000 liquidation preference (authorized - 4,000 shares; issued - 350 and 0 shares, respectively)	0
Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest	1,560,881	1,560,132
Liabilities and Equity	$ 3,184,681	$ 3,202,898