Revenues Disaggregation of Revenues (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Product revenues	$ 252.3	$ 343.3	$ 234.1
Revenues	3,181.9	3,654.1	$ 3,880.9
Natural Gas Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	163.2	134.9
Crude Oil Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	75.0	38.8
Water Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	79.6	58.0
Natural Gas Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	28.9	10.7
Natural Gas Compression
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	24.9	29.1
Crude Oil Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5.0	4.5
NGL Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	6.3	8.6
Crude Oil Pipeline
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5.2	4.8
Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	12.7	8.8
NGL Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11.7	26.9
Crude Oil Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11.0	9.3
Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	95.7	110.1
Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,726.6	1,549.6
NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	680.7	1,306.7
Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.9	0.5
NGL Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		6.1
Water Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.2	0.3
NGL Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		3.1
Product and Service, Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	253.3	343.3
Gathering and Processing Segment
Disaggregation of Revenue [Line Items]
Revenue including intersegment eliminations	1,010.8	1,139.1
Gathering and Processing Segment | Natural Gas Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	163.2	134.9
Gathering and Processing Segment | Crude Oil Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	75.0	38.8
Gathering and Processing Segment | Water Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	79.6	58.0
Gathering and Processing Segment | Natural Gas Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	28.9	10.7
Gathering and Processing Segment | Natural Gas Compression
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	24.9	29.1
Gathering and Processing Segment | Crude Oil Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.9	1.8
Gathering and Processing Segment | NGL Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Gathering and Processing Segment | Crude Oil Pipeline
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Gathering and Processing Segment | Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	7.0	2.9
Gathering and Processing Segment | NGL Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Gathering and Processing Segment | Crude Oil Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Gathering and Processing Segment | Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	56.8	55.8
Gathering and Processing Segment | Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	532.1	722.9
Gathering and Processing Segment | NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	41.4	84.2
Gathering and Processing Segment | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Gathering and Processing Segment | NGL Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.0
Gathering and Processing Segment | Water Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Gathering and Processing Segment | NGL Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.0
Gathering and Processing Segment | Product and Service, Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0.0	0.0
Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue including intersegment eliminations	34.6	27.6
Storage and Transportation | Natural Gas Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Crude Oil Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Water Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Natural Gas Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Natural Gas Compression
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Crude Oil Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5.4	4.2
Storage and Transportation | NGL Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Crude Oil Pipeline
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	7.9	7.1
Storage and Transportation | Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | NGL Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Crude Oil Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	16.7	14.3
Storage and Transportation | Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	4.6	2.0
Storage and Transportation | NGL Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.0
Storage and Transportation | Water Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Storage and Transportation | NGL Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.0
Storage and Transportation | Product and Service, Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0.0	0.0
Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue including intersegment eliminations	2,325.7
Revenues		2,690.3
Marketing Supply and Logistics | Natural Gas Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | Crude Oil Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | Water Gathering
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | Natural Gas Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | Natural Gas Compression
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | Crude Oil Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | NGL Storage
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	6.3	8.6
Marketing Supply and Logistics | Crude Oil Pipeline
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Marketing Supply and Logistics | Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	5.8	5.9
Marketing Supply and Logistics | NGL Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	11.7	26.9
Marketing Supply and Logistics | Crude Oil Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.2
Marketing Supply and Logistics | Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	72.3	70.9
Marketing Supply and Logistics | Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,315.6	978.0
Marketing Supply and Logistics | NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	659.3	1,247.0
Marketing Supply and Logistics | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1.2	0.0
Marketing Supply and Logistics | NGL Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		6.1
Marketing Supply and Logistics | Water Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.2	0.3
Marketing Supply and Logistics | NGL Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		3.1
Marketing Supply and Logistics | Product and Service, Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	253.3	343.3
Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenues	(189.2)	(202.9)
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	(2.3)	(1.5)
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	(2.7)	(2.3)
Intersegment Eliminations | Crude Oil Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(0.1)	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	(5.7)	(5.2)
Intersegment Eliminations | Natural Gas Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(33.4)	(16.6)
Intersegment Eliminations | Crude Oil Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(121.1)	(151.3)
Intersegment Eliminations | NGL Product Sales
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(20.0)	(24.5)
Intersegment Eliminations | Other revenue
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	(3.9)	(1.5)
Intersegment Eliminations | NGL Processing
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.0
Intersegment Eliminations | Water Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	0.0	0.0
Intersegment Eliminations | NGL Rail Loading
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax		0.0
Intersegment Eliminations | Product and Service, Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer	0.0	0.0
Revenue from Contract with Customer
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,928.6	3,310.8
Revenue from Contract with Customer | Gathering and Processing Segment
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	1,010.8	1,139.1
Revenue from Contract with Customer | Storage and Transportation
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	34.6	27.6
Revenue from Contract with Customer | Marketing Supply and Logistics
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	2,072.4	2,347.0
Revenue from Contract with Customer | Intersegment Eliminations
Disaggregation of Revenue [Line Items]
Revenue from Contract with Customer, Excluding Assessed Tax	$ (189.2)	$ (202.9)