Summary of Significant Accounting Policies - AFUDC (Details)			6 Months Ended	12 Months Ended
	Nov. 07, 2018	Dec. 19, 2017	Dec. 31, 2013	Dec. 31, 2018
Regulatory Assets [Line Items]
Public Utilities, Property, Plant and Equipment, Non-project Electric Utility Plant, Estimated Useful Life Average				30 years
Subsidiaries [Member]
Regulatory Assets [Line Items]
Regulated Utility, Allowed Rate of Return on Net Regulatory Assets and Liabilities	7.49%	7.60%	7.77%