Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2023

Accounting Policies [Abstract]

Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction

The following table summarizes the contractually committed fees (in millions) that we expect to recognize in our consolidated statements of operations, in either revenue or reductions to cost of sales, from MVC and firm transportation contractual provisions. Under these agreements, our customers or suppliers agree to transport or process a minimum volume of commodities on our system over an agreed period. If a customer or supplier fails to meet the minimum volume specified in such agreement, the customer or supplier is obligated to pay a contractually determined fee based upon the shortfall between actual volumes and the contractually stated volumes. All amounts in the table below are determined using the contractually-stated MVC or firm transportation volumes specified for each period multiplied by the relevant deficiency or reservation fee. Actual amounts could differ due to the timing of revenue recognition or reductions to cost of sales resulting from make-up right provisions included in our agreements, as well as due to nonpayment or nonperformance by our customers. We record revenue under MVC and firm transportation contracts during periods of shortfall when it is known that the customer cannot, or will not, make up the deficiency. These fees do not represent the shortfall amounts we expect to collect under our MVC and firm transportation contracts, as we generally do not expect volume shortfalls to equal the full amount of the contractual MVCs and firm transportation contracts during these periods.

Contractually Committed Fees	Commitments
2024	$	145.0
2025	126.2
2026	126.6
2027	105.9
2028	97.1
Thereafter	1,032.9
Total	$	1,633.7

Property, Plant and Equipment

The components of property and equipment, net of accumulated depreciation are as follows (in millions):

	Year Ended December 31,
	2023		2022
Transmission assets	$	1,459.5	$	1,452.0
Gathering systems	5,472.4		5,370.0
Natural gas processing plants and fractionation facilities	4,279.1		4,237.8
Other property and equipment	90.1		165.0
Construction in process	243.1		105.7
Property and equipment	11,544.2		11,330.5
Accumulated depreciation	(5,137.2)		(4,774.5)
Property and equipment, net of accumulated depreciation	$	6,407.0	$	6,556.0

Depreciation Expense. Depreciation is calculated using the straight-line method based on the estimated useful life of each asset, as follows:

	Useful Lives
Transmission assets	20 - 25 years
Gathering systems	20 - 25 years
Natural gas processing plants and fractionation facilities	20 - 25 years
Other property and equipment	3 - 25 years

Schedule of Gain or Loss on Disposition of Assets

The (gain) loss on disposition of assets is as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Net book value of assets disposed	$	72.9	$	30.8	$	3.3
Proceeds from sales	(73.1)		(12.8)		(4.8)
Insurance recoveries	(0.1)		—		—
(Gain) loss on disposition of assets	$	(0.3)	$	18.0	$	(1.5)

Schedule of Property and Equipment Impairment Expense

We recognized impairment expense related to property and equipment as follows (in millions):

	Year Ended December 31,
	2023		2022		2021
Property and equipment impairment (1)	$	20.7	$	—	$	0.6

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(1)During the third quarter of 2023, we identified changes in our outlook for future cash flows and the anticipated use of certain ORV crude assets in our Louisiana segment. We determined that the carrying amounts of these assets exceeded their fair values, based on market inputs and certain assumptions.

Schedules of Concentration of Risk, by Risk Factor

The following customers individually represented greater than 10% of our consolidated revenues for the years ended December 31, 2023, 2022, or 2021. No other customers represented greater than 10% of our consolidated revenues during the periods presented.

	Year Ended December 31,
	2023		2022		2021
Dow Hydrocarbons and Resources LLC	10.4	%	14.2	%	14.5	%
Marathon Petroleum Corporation	19.3	%	14.7	%	13.4	%