Description of Business and Basis of Presentation - Assets and Investments Table (Details)	Jun. 30, 2019 unit
Owned and Operated [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	17
Owned and Operated [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	35
Owned and Operated [Member] | Natural Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	24
Owned and Operated [Member] | Natural Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	2
Owned and Operated [Member] | Natural Gas Pipelines [Member]
Assets [Line Items]
Assets, number of units	5
Owned and Operated [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	3
Operated Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2
Operated Interests [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	3
Operated Interests [Member] | Natural Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	3
Operated Interests [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	1
Non-Operated Interests [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	3
Equity Investments [Member] | Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2
Equity Investments [Member] | Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	3
Equity Investments [Member] | Natural Gas Processing Plants/Trains [Member]
Assets [Line Items]
Assets, number of units	5
Equity Investments [Member] | Natural Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	4
Equity Investments [Member] | Natural Gas Pipelines [Member]
Assets [Line Items]
Assets, number of units	1
Equity Investments [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	3