Business Segments, Consolidated Revenues and Expenses (Details) - USD ($) $ in Millions		3 Months Ended								12 Months Ended
		Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Consolidated Revenues [Abstract]
Total consolidated revenues		$ 6,155.0	$ 6,307.9	$ 7,092.5	$ 7,472.5	$ 10,190.3	$ 12,330.2	$ 12,520.8	$ 12,909.9	$ 27,027.9	$ 47,951.2	$ 47,727.0
Operating costs and expenses:
Cost of sales	[1]									19,612.9	40,464.1	40,770.2
Other operating costs and expenses	[2]									2,449.4	2,541.8	2,310.4
Depreciation, amortization and accretion										1,428.2	1,282.7	1,148.9
Net losses (gains) attributable to asset sales and insurance recoveries										15.6	(102.1)	(83.4)
Non-cash asset impairment charges										162.6	34.0	92.6
General and administrative costs										192.6	214.5	188.3
Total costs and expenses										23,861.3	$ 44,435.0	$ 44,427.0
Shell Oil Company [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues										$ 1,999.3
Shell Oil Company [Member] | Revenues [Member]
Consolidated Revenues [Abstract]
Largest non-affiliated customer percentage (in hundredths)										7.40%	8.50%
BP p.l.c. [Member] | Revenues [Member]
Consolidated Revenues [Abstract]
Largest non-affiliated customer percentage (in hundredths)												9.00%
NGL Pipelines and Services [Member]
Consolidated Revenues [Abstract]
Sales of NGLs and related products										$ 8,044.8	$ 15,460.1	$ 15,916.0
Midstream services										1,743.2	1,629.7	1,204.2
Total consolidated revenues										9,788.0	17,089.8	17,120.2
NGL Pipelines and Services [Member] | Shell Oil Company [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues										400.4
Crude Oil Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Sales of crude oil										9,732.9	19,783.9	20,371.3
Midstream services										573.0	400.4	279.1
Total consolidated revenues										10,305.9	20,184.3	20,650.4
Crude Oil Pipelines & Services [Member] | Shell Oil Company [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues										1,335.8
Natural Gas Pipelines & Services [Member]
Consolidated Revenues [Abstract]
Sales of natural gas										1,722.6	3,181.7	2,571.6
Midstream services										1,020.7	1,022.1	966.9
Total consolidated revenues										2,743.3	4,203.8	3,538.5
Natural Gas Pipelines & Services [Member] | Shell Oil Company [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues										48.6
Petrochemical and Refined Products Services [Member]
Consolidated Revenues [Abstract]
Sales of petrochemicals and refined products										3,333.5	5,575.5	5,568.8
Midstream services										778.4	741.0	689.7
Total consolidated revenues										4,111.9	6,316.5	6,258.5
Petrochemical and Refined Products Services [Member] | Shell Oil Company [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues										206.5
Offshore Pipelines And Services [Member]
Consolidated Revenues [Abstract]
Sales of natural gas										0.0	0.3	0.5
Sales of crude oil										3.2	8.6	5.7
Midstream services										75.6	147.9	153.2
Total consolidated revenues										78.8	$ 156.8	$ 159.4
Offshore Pipelines And Services [Member] | Shell Oil Company [Member]
Consolidated Revenues [Abstract]
Total consolidated revenues										$ 8.0

[1] Cost of sales is a component of "Operating costs and expenses," as presented on our Statements of Consolidated Operations. Fluctuations in these amounts are primarily due to changes in energy commodity prices and sales volumes associated with our marketing activities.

[2] Represents cost of operating our plants, pipelines and other fixed assets, excluding depreciation, amortization and accretion charges.