Description of Business and Basis of Presentation - Asset Table (details) - Western Gas Partners [Member]	Mar. 31, 2015 unit
Operated [Member] | Natural Gas Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	14
Operated [Member] | Natural Gas Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	8
Operated [Member] | Natural Gas Processing Facilities [Member]
Assets [Line Items]
Assets, number of units	13
Operated [Member] | Natural Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	3
Operated [Member] | Natural Gas Pipelines [Member]
Assets [Line Items]
Assets, number of units	4
Operated [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	1
Operated Interests [Member] | Natural Gas Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2
Operated Interests [Member] | Natural Gas Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	5
Operated Interests [Member] | Natural Gas Processing Facilities [Member]
Assets [Line Items]
Assets, number of units	3
Non-Operated Interests [Member] | Natural Gas Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	5
Equity Interests [Member] | Natural Gas Gathering Systems [Member]
Assets [Line Items]
Assets, number of units	2
Equity Interests [Member] | Natural Gas Treating Facilities [Member]
Assets [Line Items]
Assets, number of units	1
Equity Interests [Member] | Natural Gas Processing Facilities [Member]
Assets [Line Items]
Assets, number of units	2
Equity Interests [Member] | Natural Gas Liquids Pipelines [Member]
Assets [Line Items]
Assets, number of units	3
Equity Interests [Member] | Oil Pipelines [Member]
Assets [Line Items]
Assets, number of units	1