Summary of Significant Accounting and Reporting Policies - Narrative (Details) $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($) pipeline	Dec. 31, 2019 USD ($)
Property, Plant and Equipment [Line Items]
Restricted cash, current | $	$ 8	$ 3
Non Affiliated Party [Member]
Property, Plant and Equipment [Line Items]
Number Of Pipelines | pipeline	1
NEP OpCo [Member]
Property, Plant and Equipment [Line Items]
Noncontrolling ownership interest	60.80%
NEP OpCo [Member] | Non Affiliated Party [Member]
Property, Plant and Equipment [Line Items]
Noncontrolling ownership interest	10.00%
Silver State [Member]
Property, Plant and Equipment [Line Items]
Noncontrolling ownership interest	50.00%