Investments in Unconsolidated Affiliates - Activity Related to Partnership's Investments in Unconsolidated Affiliates (Parenthetical) (Details) - USD ($) $ in Millions |
3 Months Ended | |
---|---|---|
Mar. 31, 2018 |
Mar. 31, 2017 |
|
Schedule Of Equity Method Investments [Line Items] | ||
Return of capital from unconsolidated affiliates | $ 1.5 | |
Contributions of property, plant and equipment | 16.0 | $ 1.0 |
Little Missouri 4 [Member] | ||
Schedule Of Equity Method Investments [Line Items] | ||
Contributions of property, plant and equipment | 16.0 | |
Targa Resources Partners LP [Member] | ||
Schedule Of Equity Method Investments [Line Items] | ||
Return of capital from unconsolidated affiliates | 1.5 | |
Targa Resources Partners LP [Member] | Little Missouri 4 [Member] | ||
Schedule Of Equity Method Investments [Line Items] | ||
Return of capital from unconsolidated affiliates | $ 8.0 |