| Document and Entity Information | Jul. 14, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 14, 2020 |
| Entity Registrant Name | TerraForm Power, Inc. |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-36542 |
| Entity Tax Identification Number | 46-4780940 |
| Entity Address, Address Line One | 200 Liberty Street |
| Entity Address, Address Line Two | 14th Floor |
| Entity Address, City or Town | New York |
| Entity Address, State or Province | NY |
| Entity Address, Postal Zip Code | 10281 |
| City Area Code | 646 |
| Local Phone Number | 992-2400 |
| Written Communications | true |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Entity Emerging Growth Company | false |
| Entity Central Index Key | 0001599947 |
| Title of 12(b) Security | Common Stock, Class A, par value $0.01 |
| Trading Symbol | TERP |
| Security Exchange Name | NASDAQ |
