Segment Information - Summary of Consolidated Revenues Disaggregated by Product and Service (Details) - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Revenue from External Customer [Line Items]
Revenue recognized		$ 1,964.7	$ 2,212.5
Non-customer revenue		11.8	(38.8)
Total revenues		2,299.4	2,455.6
Derivative Activities - Hedge [Member]
Revenue from External Customer [Line Items]
Non-customer revenue		21.3	(28.0)
Derivative Activities - Non-hedge [Member]
Revenue from External Customer [Line Items]
Non-customer revenue	[1]	(9.5)	(10.8)
Natural Gas [Member]
Revenue from External Customer [Line Items]
Revenue recognized		411.3	470.1
NGL [Member]
Revenue from External Customer [Line Items]
Revenue recognized		1,408.1	1,607.3
Condensate and Crude Oil [Member]
Revenue from External Customer [Line Items]
Revenue recognized		137.7	86.9
Petroleum Products [Member]
Revenue from External Customer [Line Items]
Revenue recognized		7.6	48.2
Gathering and Processing Fees [Member]
Revenue from External Customer [Line Items]
Total revenues		194.5	152.1
Sales of Commodities [Member]
Revenue from External Customer [Line Items]
Total revenues		1,976.5	2,173.7
Other [Member]
Revenue from External Customer [Line Items]
Total revenues		12.6	10.5
NGL Transportation and Services [Member]
Revenue from External Customer [Line Items]
Total revenues		36.2	41.1
Storage Terminaling and Export [Member]
Revenue from External Customer [Line Items]
Total revenues		79.6	78.2
Fees from Midstream Services [Member]
Revenue from External Customer [Line Items]
Total revenues		$ 322.9	$ 281.9

[1] Represents derivative activities that are not designated as hedging instruments under ASC 815.