Property, Plant and Equipment - Additional Information (Details) - USD ($)	3 Months Ended			12 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	[1]	Dec. 31, 2018
Property, Plant and Equipment [Line Items]
Impairments	$ 390,000	$ 200,000		$ 230,600,000
Third Creek Gathering System [Member]
Property, Plant and Equipment [Line Items]
Impairments				125,900,000
Third Creek Gathering System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value				1,800,000
Kitty Draw Gathering System [Member]
Property, Plant and Equipment [Line Items]
Impairments				8,100,000
Kitty Draw Gathering System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value				0
Hilight System [Member]
Property, Plant and Equipment [Line Items]
Impairments				38,700,000
Hilight System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value				4,900,000
MIGC System [Member]
Property, Plant and Equipment [Line Items]
Impairments				34,600,000
MIGC System [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value				15,200,000
Equipment [Member]
Property, Plant and Equipment [Line Items]
Impairments				23,300,000
GNB NGL Pipeline [Member]
Property, Plant and Equipment [Line Items]
Impairments				10,900,000
GNB NGL Pipeline [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Income Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated fair value				10,000,000
Chipeta Complex [Member]
Property, Plant and Equipment [Line Items]
Impairments				5,600,000
Chipeta Complex [Member] | Fair Value, Measurements, Nonrecurring [Member] | Level 3 Inputs [Member] | Valuation, Market Approach [Member]
Property, Plant and Equipment [Line Items]
Estimated salvage value				$ 1,500,000

[1] Financial information has been recast to include the financial position and results attributable to AMA. See Note 1 and Note 3.