Condensed Consolidating Guarantor Financial Statements - Balance Sheets (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014	Dec. 31, 2013
Condensed Balance Sheet Statements, Captions [Line Items]
Payments for Repurchase of Common Stock	$ 4,259	$ 719
Payments of Ordinary Dividends, Common Stock	49,836	31,149
Current assets:
Cash and cash equivalents	145,993	67,049	$ 40,598	$ 79,351
Restricted cash	0		6,980
Accounts receivable, net	333,157		351,334
Receivable from affiliates	7,833		16,819
Inventories	63,857		43,532
Other current assets	20,401		20,017
Total current assets	571,241		479,280
Property, plant and equipment, net	1,474,947		1,256,825
Equity method investments	547,448		577,920
Goodwill	57,592		58,326
Other intangible assets, net	164,840		173,065
Other noncurrent assets, net	61,500		44,386
Total assets	2,877,568		2,589,802
Current liabilities:
Accounts payable	263,625		257,177
Payable to affiliates	11,150		13,460
Accrued liabilities	90,584		92,694
Payables to pre-petition creditors	0		3,129
Deferred revenue	11,403		23,688
Other current liabilities	1,371		1,474
Current portion of long-term debt	37		40
Total current liabilities	378,170		391,662
Long-term debt	1,044,468		767,092
Deferred income taxes	198,297		161,956
Other noncurrent liabilities	$ 22,471		$ 49,655
Commitments and contingencies
Owners’ equity excluding noncontrolling interests in consolidated subsidiaries	$ 1,141,322		$ 1,149,508
Noncontrolling interests in consolidated subsidiaries	92,840		69,929
Total owners’ equity	1,234,162		1,219,437
Total liabilities and owners’ equity	2,877,568		2,589,802
Parent Company [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Payments for Repurchase of Common Stock	4,259	719
Payments of Ordinary Dividends, Common Stock	49,836	31,149
Current assets:
Cash and cash equivalents	40,950	5,696	9,254	2,545
Restricted cash			3,856
Accounts receivable, net	706		9,669
Receivable from affiliates	921		2,512
Inventories	0		0
Other current assets	9,564		10,498
Total current assets	52,141		35,789
Property, plant and equipment, net	4,728		4,112
Equity method investments	1,514,132		1,551,825
Goodwill	0		0
Other intangible assets, net	22		26
Other noncurrent assets, net	40,240		24,555
Total assets	1,611,263		1,616,307
Current liabilities:
Accounts payable	574		649
Payable to affiliates	211		21
Accrued liabilities	14,453		11,993
Payables to pre-petition creditors			3,129
Deferred revenue	0		0
Other current liabilities	461		224
Current portion of long-term debt	0		0
Total current liabilities	15,699		16,016
Long-term debt	300,000		335,000
Deferred income taxes	151,785		112,897
Other noncurrent liabilities	$ 2,457		$ 2,886
Commitments and contingencies
Owners’ equity excluding noncontrolling interests in consolidated subsidiaries	$ 1,141,322		$ 1,149,508
Noncontrolling interests in consolidated subsidiaries	0		0
Total owners’ equity	1,141,322		1,149,508
Total liabilities and owners’ equity	1,611,263		1,616,307
Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Payments for Repurchase of Common Stock	0	0
Payments of Ordinary Dividends, Common Stock	0	0
Current assets:
Cash and cash equivalents	0	0	0	0
Restricted cash			0
Accounts receivable, net	26,789		32,056
Receivable from affiliates	1,318		6,624
Inventories	963		248
Other current assets	550		575
Total current assets	29,620		39,503
Property, plant and equipment, net	527,799		452,352
Equity method investments	417,621		348,115
Goodwill	13,052		13,052
Other intangible assets, net	146,233		152,383
Other noncurrent assets, net	3,168		958
Total assets	1,137,493		1,006,363
Current liabilities:
Accounts payable	15,267		22,097
Payable to affiliates	10		7
Accrued liabilities	12,495		17,575
Payables to pre-petition creditors			0
Deferred revenue	0		0
Other current liabilities	0		707
Current portion of long-term debt	0		0
Total current liabilities	27,772		40,386
Long-term debt	7,520		0
Deferred income taxes	0		0
Other noncurrent liabilities	$ 0		$ 0
Commitments and contingencies
Owners’ equity excluding noncontrolling interests in consolidated subsidiaries	$ 1,102,201		$ 965,977
Noncontrolling interests in consolidated subsidiaries	0		0
Total owners’ equity	1,102,201		965,977
Total liabilities and owners’ equity	1,137,493		1,006,363
Non-Guarantor Subsidiaries [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Payments for Repurchase of Common Stock	0	0
Payments of Ordinary Dividends, Common Stock	0	0
Current assets:
Cash and cash equivalents	108,628	64,789	35,445	78,342
Restricted cash			3,124
Accounts receivable, net	305,662		309,609
Receivable from affiliates	8,050		15,659
Inventories	62,894		43,284
Other current assets	10,287		8,944
Total current assets	495,521		416,065
Property, plant and equipment, net	942,420		800,361
Equity method investments	430,168		415,673
Goodwill	44,540		45,274
Other intangible assets, net	18,585		20,656
Other noncurrent assets, net	18,092		18,873
Total assets	1,949,326		1,716,902
Current liabilities:
Accounts payable	247,784		234,431
Payable to affiliates	13,386		21,406
Accrued liabilities	63,639		63,126
Payables to pre-petition creditors			0
Deferred revenue	11,403		23,688
Other current liabilities	910		543
Current portion of long-term debt	37		40
Total current liabilities	337,159		343,234
Long-term debt	760,968		490,946
Deferred income taxes	46,512		49,059
Other noncurrent liabilities	$ 20,014		$ 46,769
Commitments and contingencies
Owners’ equity excluding noncontrolling interests in consolidated subsidiaries	$ 691,833		$ 716,965
Noncontrolling interests in consolidated subsidiaries	92,840		69,929
Total owners’ equity	784,673		786,894
Total liabilities and owners’ equity	1,949,326		1,716,902
Consolidation, Eliminations [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Payments for Repurchase of Common Stock	0	0
Payments of Ordinary Dividends, Common Stock	0	0
Current assets:
Cash and cash equivalents	(3,585)	$ (3,436)	(4,101)	$ (1,536)
Restricted cash			0
Accounts receivable, net	0		0
Receivable from affiliates	(2,456)		(7,976)
Inventories	0		0
Other current assets	0		0
Total current assets	(6,041)		(12,077)
Property, plant and equipment, net	0		0
Equity method investments	(1,814,473)		(1,737,693)
Goodwill	0		0
Other intangible assets, net	0		0
Other noncurrent assets, net	0		0
Total assets	(1,820,514)		(1,749,770)
Current liabilities:
Accounts payable	0		0
Payable to affiliates	(2,457)		(7,974)
Accrued liabilities	(3)		0
Payables to pre-petition creditors			0
Deferred revenue	0		0
Other current liabilities	0		0
Current portion of long-term debt	0		0
Total current liabilities	(2,460)		(7,974)
Long-term debt	(24,020)		(58,854)
Deferred income taxes	0		0
Other noncurrent liabilities	$ 0		$ 0
Commitments and contingencies
Owners’ equity excluding noncontrolling interests in consolidated subsidiaries	$ (1,794,034)		$ (1,682,942)
Noncontrolling interests in consolidated subsidiaries	0		0
Total owners’ equity	(1,794,034)		(1,682,942)
Total liabilities and owners’ equity	$ (1,820,514)		$ (1,749,770)