Length of transmission line.

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- Definition

Number of Substations

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- Definition

Payments to Acquire Equity Method Investments, Additional Outstanding Capital Commitments

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- Definition

Voltage Of Substations

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- Definition

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3213-108585

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- Definition

Amount of distribution received from equity method investee for return of investment, classified as investing activities. Excludes distribution for return on investment, classified as operating activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21D
-URI http://asc.fasb.org/extlink&oid=98514028&loc=SL94080555-108585

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Commitments and Contingencies - Investments in Affiliates and Other Entities (Detail) $ in Millions	12 Months Ended	36 Months Ended
	Dec. 31, 2019 USD ($)	Sep. 30, 2017 USD ($)	May 31, 2022 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2014 kV substation km
Other Commitments, Planned Oil and Gas Infrastructure Projects
Other Commitments [Line Items]
Outstanding capital commitment		$ 17.3
Capital for infrastructure projects
Other Commitments [Line Items]
Outstanding capital commitment		80.0
Scenario, Forecast \| Other Commitments, Planned Oil and Gas Infrastructure Projects
Other Commitments [Line Items]
Outstanding capital commitment			$ 16.9	$ 0.4
EPC Electric Transmission Project
Other Commitments [Line Items]
Length of electrical transmission line to be constructed under contract \| km					500
Number of substations \| substation					2
Voltage of substations \| kV					500
Aggregate contributions to this unconsolidated affiliate		67.3
Proceeds from return of capital		3.1
EPC Electric Transmission Project \| Scenario, Forecast
Other Commitments [Line Items]
Additional aggregate contributions to this unconsolidated affiliate	$ 25.4
Infrastructure investors partnership \| Capital for infrastructure projects
Other Commitments [Line Items]
Outstanding capital commitment		$ 1,000.0