Commitments and Contingencies - PG&E Bankruptcy (Details)	12 Months Ended
Dec. 31, 2018 USD ($)
Commitments and Contingencies Disclosure [Abstract]
Net income attributable to NEP was from PPAs	12.00%
Total financings	$ 682,000,000
Total financings reclassified into current debt	641,000,000
Impairment adjustment	$ 0

Amount of outstanding long-term debt or borrowing associated with any securities or credit agreement for which there has been a default in principal, interest, sinking fund, or redemption provisions, or any breach of covenant that existed at the end of the period and subsequently has not been cured.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(c))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Name:	us-gaap_DebtDefaultLongtermDebtAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant