Variable Interest Entities - Additional Information (Details) $ in Millions	12 Months Ended
Dec. 31, 2018 USD ($) MW	Dec. 31, 2017 USD ($)
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 113	$ 7
Texas Solar 4 \| Noncontrolling Interest
Variable Interest Entity [Line Items]
Noncontrolling interest	$ 7
Texas Solar 4 \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
Generating capacity (MW AC) \| MW	40
VIE consolidated, carrying amount, assets and liabilities, net	$ 27	$ 26
Texas Solar 4 \| Variable Interest Entity, Primary Beneficiary \| Con Edison Development
Variable Interest Entity [Line Items]
Percentage of variable interests (less than)	80.00%
Tax Equity Projects \| Variable Interest Entity, Primary Beneficiary
Variable Interest Entity [Line Items]
VIE consolidated, carrying amount, assets and liabilities, net	$ 870
Noncontrolling interest	$ 104
Tax Equity Projects \| Variable Interest Entity, Primary Beneficiary \| Con Edison Development
Variable Interest Entity [Line Items]
Percentage of variable interests (less than)	100.00%

Generating Capacity

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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(a)(24))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.31)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(22))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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- Definition

The net carrying amount of the consolidated Variable Interest Entity's assets and liabilities included in the reporting entity's statement of financial position.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (bb)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5710-111685

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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.

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- Definition

Percentage of the Variable Interest Entity's (VIE) voting interest owned by (or beneficial interest in) the reporting entity (directly or indirectly).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 810
-SubTopic 10
-Section 50
-Paragraph 5A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=108788376&loc=SL6759159-111685

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