Summary of Significant Accounting Policies - (Narrative) (Details) - Affiliated Entity - Penn East Pipeline Company LLC	Dec. 31, 2020
UGI Penn East LLC
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity method investment ownership percent	20.00%
Southern Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity method investment ownership percent	20.00%
New Jersey Resources
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity method investment ownership percent	20.00%
South Jersey Industries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity method investment ownership percent	20.00%
Enbridge Inc
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Equity method investment ownership percent	20.00%