Risk Concentrations (Schedule of Foreign Revenues) (Details) - USD ($) $ in Thousands	3 Months Ended									9 Months Ended	12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Oct. 01, 2016	Dec. 31, 2018	Dec. 31, 2017
Concentration Risk [Line Items]
Revenues	$ 650,963	$ 633,180	$ 592,349	$ 575,295	$ 560,244	$ 613,538	$ 549,866	$ 600,975	$ 575,688		$ 2,451,787	$ 2,324,623
Europe
Concentration Risk [Line Items]
Revenues									61,169		559,165	388,926
Asia
Concentration Risk [Line Items]
Revenues									55,634		452,711	264,503
Central and South America
Concentration Risk [Line Items]
Revenues									13,224		79,085	30,982
Africa
Concentration Risk [Line Items]
Revenues									0		17,567	14,901
Brokered Sales
Concentration Risk [Line Items]
Revenues									0		2,372	3,150
Foreign Countries
Concentration Risk [Line Items]
Revenues									$ 130,027		$ 1,110,900	$ 702,462
Predecessor
Concentration Risk [Line Items]
Revenues										$ 1,398,709
Predecessor | Europe
Concentration Risk [Line Items]
Revenues										112,986
Predecessor | Asia
Concentration Risk [Line Items]
Revenues										68,536
Predecessor | Central and South America
Concentration Risk [Line Items]
Revenues										41,861
Predecessor | Africa
Concentration Risk [Line Items]
Revenues										0
Predecessor | Brokered Sales
Concentration Risk [Line Items]
Revenues										0
Predecessor | Foreign Countries
Concentration Risk [Line Items]
Revenues										$ 223,383