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- Definition

EPA Proposed Penalty

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- Definition

Estimated cost of proposed supplemental environmental projects

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- Definition

Term Of Agreements

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- Definition

Total costs accrued as of the balance sheet date for environmental loss contingencies.

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- Definition

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

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- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

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Maximum potential amount of future payments (undiscounted) the guarantor could be required to make under the guarantee or each group of similar guarantees before reduction for potential recoveries under recourse or collateralization provisions.

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Minimum amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend funds to procure goods or services, excluding long-term purchase commitments or unconditional purchase obligations.

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Commitments and Contingencies (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Feb. 15, 2017
Commitments And Contingencies [Line Items]
Accrual for environmental loss contingencies	$ 19.0	$ 20.0
Contractual commitments to acquire property, plant and equipment	753.0
Environmental Loss Contingency [Member] \| MPC
Commitments And Contingencies [Line Items]
Receivable from MPC for indemnification of environmental costs	0.0	$ 0.0
MarkWest, MarkWest Liberty Midstream, Ohio Fractionation, MarkWest Utica EMG [Member]
Commitments And Contingencies [Line Items]
EPA proposed penalty	0.9
Estimated cost of proposed supplemental environmental projects	$ 3.3
Bakken Pipeline System
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage			9.00%
Indirect Ownership Interest \| Bakken Pipeline System
Commitments And Contingencies [Line Items]
Equity method investment, ownership percentage	9.00%
Guarantee Type, Other [Member]
Commitments And Contingencies [Line Items]
Guarantor Obligations, Maximum Exposure, Undiscounted	$ 230.0
Minimum \| Minimum Committed Volume Contracts [Member]
Commitments And Contingencies [Line Items]
Term Of Agreements	4 years