Derivative Instruments, Hedging Activities and Fair Value Measurements, Nonrecurring Fair Value Measurements (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Asset Impairment Charges [Abstract]
Asset impairment charges		$ 6.8	$ 26.8	$ 22.0	$ 139.1
Impairment of other current assets				1.2
Impairment of long-lived assets disposed of other than by sale				11.3	69.9
Impairment of long-lived assets held for sale				9.5	14.2
Impairment of long-lived assets disposed of by sale	[1]				55.0
Impairment of long-lived assets				20.8	139.1
NGL Pipelines & Services [Member]
Asset Impairment Charges [Abstract]
Asset impairment charges		3.8	14.6	6.4	20.6
Crude Oil Pipelines & Services [Member]
Asset Impairment Charges [Abstract]
Asset impairment charges		0.0	0.0	0.9	25.9
Natural Gas Pipelines & Services [Member]
Asset Impairment Charges [Abstract]
Asset impairment charges		2.0	0.0	11.7	21.5
Petrochemical & Refined Products Services [Member]
Asset Impairment Charges [Abstract]
Asset impairment charges		1.0	12.2	3.0	12.6
Offshore Pipelines & Services [Member]
Asset Impairment Charges [Abstract]
Asset impairment charges		0.0	0.0	0.0	58.5
Fair Value, Measurements, Nonrecurring [Member] | Long-lived Assets Disposed of Other Than By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		0.0	0.4	0.0	0.4
Fair Value, Measurements, Nonrecurring [Member] | Long-lived Assets Held For Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		1.5	34.2	1.5	34.2
Fair Value, Measurements, Nonrecurring [Member] | Long-lived Assets Disposed of By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value			0.0		0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member] | Long-lived Assets Disposed of Other Than By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		0.0	0.0	0.0	0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member] | Long-lived Assets Held For Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		0.0	0.0	0.0	0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 1 [Member] | Long-lived Assets Disposed of By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value			0.0		0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member] | Long-lived Assets Disposed of Other Than By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		0.0	0.0	0.0	0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member] | Long-lived Assets Held For Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		1.5	0.0	1.5	0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 2 [Member] | Long-lived Assets Disposed of By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value			0.0		0.0
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Long-lived Assets Disposed of Other Than By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		0.0	0.4	0.0	0.4
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Long-lived Assets Held For Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value		$ 0.0	34.2	$ 0.0	34.2
Fair Value, Measurements, Nonrecurring [Member] | Level 3 [Member] | Long-lived Assets Disposed of By Sale [Member]
Assets, Fair Value Disclosure [Abstract]
Assets, fair value			$ 0.0		$ 0.0

[1] Primarily represents the impairment charge recorded in connection with the sale of our Offshore Business.