Property, Plant and Equipment, Other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Mar. 29, 2018
Assets acquired:
Capital expenditures	$ 4,223.2	$ 3,101.8	$ 2,984.1
Common units issued in connection with land acquisition (in units)	1,223,242
Sale of Assets:
Proceeds from asset sales	$ 161.2	40.1	46.5
Gains attributable to asset sales	28.7	10.7	2.5
Land [Member]
Assets acquired:
Property, plant and equipment, additions	85.2
Capital expenditures	55.2
Red River System [Member]
Sale of Assets:
Proceeds from asset sales	134.9	0.0	0.0
Gains attributable to asset sales	$ 20.6	$ 0.0	$ 0.0
Delaware Basin Gas Processing LLC [Member]
Business Acquisition [Line Items]
Remaining membership interest acquired				50.00%
Assets acquired:
Property, plant, and equipment				$ 200.0