Investments in Unconsolidated Affiliates (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	$ 2,654.3		$ 2,615.1
Equity in income (loss) of unconsolidated affiliates by business segment [Abstract]
Equity in income (loss) of unconsolidated affiliates	154.6	$ 115.7
Income Statement Data:
Revenues	516.5	396.0
Operating income	338.5	243.7
Net income	337.6	242.3
NGL Pipelines & Services [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	670.3		662.0
Equity in income (loss) of unconsolidated affiliates by business segment [Abstract]
Equity in income (loss) of unconsolidated affiliates	30.1	19.4
Crude Oil Pipelines & Services [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	1,898.0		1,867.5
Equity in income (loss) of unconsolidated affiliates by business segment [Abstract]
Equity in income (loss) of unconsolidated affiliates	124.6	97.9
Natural Gas Pipelines & Services [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	23.2		22.8
Equity in income (loss) of unconsolidated affiliates by business segment [Abstract]
Equity in income (loss) of unconsolidated affiliates	1.7	1.0
Petrochemical & Refined Products Services [Member]
Schedule of Equity Method Investments [Line Items]
Investments in unconsolidated affiliates	62.8		$ 62.8
Equity in income (loss) of unconsolidated affiliates by business segment [Abstract]
Equity in income (loss) of unconsolidated affiliates	$ (1.8)	$ (2.6)