Commitments and Contingencies - Investment Arrangements (Details) $ in Thousands	9 Months Ended
Sep. 30, 2021 USD ($) constructionProject	Dec. 31, 2020 USD ($)
Other Commitments [Line Items]
Number of joint ventures \| constructionProject	3
Cash	$ 239,924	$ 423,118
Proportionately Consolidated Non-Controlled Joint Venture
Other Commitments [Line Items]
Cash	10,800	$ 8,200
Payments for advance to affiliate	$ 700
Proportionately Consolidated Non-Controlled Joint Venture \| Joint Ventures That Provide Electrical Transmission Infrastructure Services \| Minimum
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	85.00%
Proportionately Consolidated Non-Controlled Joint Venture \| Joint Ventures That Provide Electrical Transmission Infrastructure Services \| Maximum
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	90.00%
Proportionately Consolidated Non-Controlled Joint Venture \| Joint Venture Civil Construction Project \| Minimum
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	30.00%
Proportionately Consolidated Non-Controlled Joint Venture \| Joint Venture Civil Construction Project \| Maximum
Other Commitments [Line Items]
Proportionately consolidated non-controlled joint venture, ownership percentage	50.00%

Number of joint ventures in which the Company has an interest.

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- Definition

The percentage interest in a proportionately consolidated joint venture.

+ References

No definition available.

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- Definition

Amount of currency on hand as well as demand deposits with banks or financial institutions. Includes other kinds of accounts that have the general characteristics of demand deposits. Also includes short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3044-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.1)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

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.

+ References

No definition available.

+ Details

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- Definition

The cash outflow from advancing money to an affiliate (an entity that is related but not strictly controlled by the entity).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3213-108585

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