Subsidiary Guarantors Consolidated Balance Sheet (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Condensed Balance Sheet Statements, Captions [Line Items]
Receivables, Intercompany	$ 0	$ 0
Other Assets, Current	257,170	279,182
Property, Plant and Equipment, Net	1,881,456	1,184,525
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other Assets	7,064	958
Assets	2,145,690	1,464,665	$ 1,140,861
Payables, Intercompany	0	0
Other Sundry Liabilities, Current	282,606	169,505
Unsecured Long-term Debt, Noncurrent	574,073	573,924
Other Sundry Liabilities, Noncurrent	31,465	29,791
Stockholders' Equity Attributable to Parent	1,156,556	690,125
Non-controlling interest in subsidiaries	100,990	1,320
Liabilities and Equity	$ 2,145,690	1,464,665
Subsidiary ownership percentage	100.00%
Consolidation, Eliminations [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Receivables, Intercompany	$ (588,021)	(332,453)
Other Assets, Current	0	0
Property, Plant and Equipment, Net	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(1,258,372)	(947,037)
Other Assets	(3,003)	0
Assets	(1,849,396)	(1,279,490)
Payables, Intercompany	(588,021)	(332,453)
Other Sundry Liabilities, Current	(274)	0
Unsecured Long-term Debt, Noncurrent	0	0
Other Sundry Liabilities, Noncurrent	(2,729)	0
Stockholders' Equity Attributable to Parent	(1,258,372)	(947,037)
Non-controlling interest in subsidiaries	0	0
Liabilities and Equity	(1,849,396)	(1,279,490)
Parent Company [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Receivables, Intercompany	585,109	316,791
Other Assets, Current	2,240	101,102
Property, Plant and Equipment, Net	0	33
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	1,147,295	856,762
Other Assets	6,425	0
Assets	1,741,069	1,274,688
Payables, Intercompany	0	0
Other Sundry Liabilities, Current	8,847	9,265
Unsecured Long-term Debt, Noncurrent	574,073	573,924
Other Sundry Liabilities, Noncurrent	1,593	1,374
Stockholders' Equity Attributable to Parent	1,156,556	690,125
Non-controlling interest in subsidiaries	0	0
Liabilities and Equity	1,741,069	1,274,688
Non-Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Receivables, Intercompany	2,912	3,571
Other Assets, Current	9,334	4,242
Property, Plant and Equipment, Net	223,178	113,107
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Other Assets	0	0
Assets	235,424	120,920
Payables, Intercompany	0	12,091
Other Sundry Liabilities, Current	19,891	16,632
Unsecured Long-term Debt, Noncurrent	0	0
Other Sundry Liabilities, Noncurrent	3,466	602
Stockholders' Equity Attributable to Parent	111,077	90,275
Non-controlling interest in subsidiaries	100,990	1,320
Liabilities and Equity	235,424	120,920
Guarantor Subsidiaries [Member] | Reportable Legal Entities [Member]
Condensed Balance Sheet Statements, Captions [Line Items]
Receivables, Intercompany	0	12,091
Other Assets, Current	245,596	173,838
Property, Plant and Equipment, Net	1,658,278	1,071,385
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	111,077	90,275
Other Assets	3,642	958
Assets	2,018,593	1,348,547
Payables, Intercompany	588,021	320,362
Other Sundry Liabilities, Current	254,142	143,608
Unsecured Long-term Debt, Noncurrent	0	0
Other Sundry Liabilities, Noncurrent	29,135	27,815
Stockholders' Equity Attributable to Parent	1,147,295	856,762
Non-controlling interest in subsidiaries	0	0
Liabilities and Equity	$ 2,018,593	$ 1,348,547