Revenue Recognition Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Disaggregation of Revenue [Line Items]
Revenues	$ 727.9	$ 835.2
Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenues	214.9	182.3
Revenue including intersegment eliminations	254.9	235.1
Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenues	3.5	7.8
Revenue including intersegment eliminations	6.1	11.4
Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenues	509.5	645.1
Revenue including intersegment eliminations	509.5
Natural Gas Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	43.8	30.2
Natural Gas Gathering | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	43.8	30.2
Natural Gas Gathering | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Gathering | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	26.5	15.3
Crude Oil Gathering | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	26.5	15.3
Crude Oil Gathering | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Gathering | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Water Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	23.0	16.8
Water Gathering | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	23.0	16.8
Water Gathering | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Water Gathering | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	10.2	2.5
Natural Gas Processing | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	10.2	2.5
Natural Gas Processing | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Processing | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Compression
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	6.3	6.0
Natural Gas Compression | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	6.3	6.0
Natural Gas Compression | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Compression | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.7	1.2
Crude Oil Storage | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.5	0.5
Crude Oil Storage | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.6	1.4
Crude Oil Storage | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
NGL Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.6	1.3
NGL Storage | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
NGL Storage | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
NGL Storage | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.6	1.3
Crude Oil Pipeline
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.1	1.0
Crude Oil Pipeline | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Pipeline | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.6	1.7
Crude Oil Pipeline | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3.6	3.0
Crude Oil Transportation | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2.0	1.5
Crude Oil Transportation | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Transportation | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.6	1.5
NGL Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.7	4.1
NGL Transportation | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
NGL Transportation | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
NGL Transportation | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.7	4.1
Crude Oil Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2.0	5.8
Crude Oil Rail Loading | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Rail Loading | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	3.4	7.2
Crude Oil Rail Loading | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	18.6	34.5
Natural Gas Product Sales | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	12.0	18.8
Natural Gas Product Sales | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Natural Gas Product Sales | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	18.3	22.3
Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	355.0	378.4
Crude Oil Product Sales | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	121.1	131.6
Crude Oil Product Sales | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Crude Oil Product Sales | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	250.2	290.1
NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	157.9	230.6
NGL Product Sales | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	9.5	11.9
NGL Product Sales | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
NGL Product Sales | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	160.3	221.5
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.6	0.2
Other revenue | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Other revenue | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.5	1.1
Other revenue | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.5	0.0
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(42.6)	(56.4)
Intersegment Eliminations | Natural Gas Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Crude Oil Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Water Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Natural Gas Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Natural Gas Compression
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Crude Oil Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(0.4)	(0.7)
Intersegment Eliminations | NGL Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Crude Oil Pipeline
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(0.5)	(0.7)
Intersegment Eliminations | Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | NGL Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | Crude Oil Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(1.4)	(1.4)
Intersegment Eliminations | Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(11.7)	(6.6)
Intersegment Eliminations | Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(16.3)	(43.3)
Intersegment Eliminations | NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(11.9)	(2.8)
Intersegment Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(0.4)	(0.9)
Revenue from Contract with Customer
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	652.6	730.9
Revenue from Contract with Customer | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	254.9	235.1
Revenue from Contract with Customer | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	6.1	11.4
Revenue from Contract with Customer | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	434.2	540.8
Revenue from Contract with Customer | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(42.6)	(56.4)
Product and Service, Other
Disaggregation of Revenue [Line Items]
Non-Topic 606 revenues	75.3	104.3
Product and Service, Other | Gathering and Processing Operations
Disaggregation of Revenue [Line Items]
Non-Topic 606 revenues	0.0	0.0
Product and Service, Other | Storage and Transportation
Disaggregation of Revenue [Line Items]
Non-Topic 606 revenues	0.0	0.0
Product and Service, Other | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Non-Topic 606 revenues	75.3	104.3
Product and Service, Other | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Non-Topic 606 revenues	$ 0.0	$ 0.0