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Variable Interest Entities (Pipeline Investments) (Details) - USD ($) $ in Millions | 9 Months Ended |
--- | --- | ---
Sep. 30, 2018 | Dec. 31, 2017
Variable Interest Entities [Line Items] |  |
Investments in joint ventures | $ 1,328 | $ 1,175
Variable Interest Entity, Not Primary Beneficiary [Member] |  |
Variable Interest Entities [Line Items] |  |
Variable interest entity, nonconsolidated, carrying amount, liabilities | 28 | 29
Investments in joint ventures | 966 | 919
Piedmont Natural Gas [Member] |  |
Variable Interest Entities [Line Items] |  |
Investments in joint ventures | $ 63 | 61
Atlantic Coast Pipeline [Member] |  |
Variable Interest Entities [Line Items] |  |
Ownership percentage | 47.00% |
Atlantic Coast Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] |  |
Variable Interest Entities [Line Items] |  |
Equity method investment, line of credit facility, maximum borrowing capacity |  | 3,400
Investments in joint ventures | $ 704 | 397
Atlantic Coast Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] | Revolving Credit Facility [Member] |  |
Variable Interest Entities [Line Items] |  |
Variable interest entity, entity maximum loss exposure, percent | 47.00% |
Variable interest entity, nonconsolidated, carrying amount, liabilities | $ 486 |
Sabal Trail Transmission Pipeline [Member] |  |
Variable Interest Entities [Line Items] |  |
Investments in joint ventures | $ 112 |
Ownership percentage | 7.50% |
Sabal Trail Transmission Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] |  |
Variable Interest Entities [Line Items] |  |
Investments in joint ventures |  | 219
Constitution Pipeline [Member] |  |
Variable Interest Entities [Line Items] |  |
Ownership percentage | 24.00% |
Constitution Pipeline [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] |  |
Variable Interest Entities [Line Items] |  |
Equity method investment, OTTI | $ 55 |
Investments in joint ventures | 25 | 81
Pipeline Investments [Member] | Variable Interest Entity, Not Primary Beneficiary [Member] |  |
Variable Interest Entities [Line Items] |  |
Investments in joint ventures | $ 729 | $ 697

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- Definition Maximum borrowing capacity, for the equity method investment that is not consolidated, under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + References No definition available. + Details
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- Definition The reporting entity's maximum percentage of exposure to loss as a result of its involvement with the Variable Interest Entity (VIE). + References No definition available. + Details
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- Definition This item represents an other than temporary decline in value that has been recognized against an investment accounted for under the equity method of accounting. The excess of the carrying amount over the fair value of the investment represents the amount of the write down which is or was reflected in earnings. The written down value is a new cost basis with the adjusted value of the investment becoming its new carrying value subject to the equity accounting method. Evidence of a loss in value might include, but would not necessarily be limited to, absence of an ability to recover the carrying amount of the investment or inability of the investee to sustain an earnings capacity which would justify the carrying amount of the investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 35 -Paragraph 32 -URI http://asc.fasb.org/extlink&oid=114001220&loc=d3e32787-111569 + Details
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- Definition This item represents the carrying amount on the entity's balance sheet of its investment in common stock of an equity method investee. This is not an indicator of the fair value of the investment, rather it is the initial cost adjusted for the entity's share of earnings and losses of the investee, adjusted for any distributions (dividends) and other than temporary impairment (OTTI) losses recognized. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 45 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=109237563&loc=d3e33749-111570 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 280 -SubTopic 10 -Section 50 -Paragraph 25 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=115929826&loc=d3e8813-108599 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 210.5-02.12) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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- Definition Carrying amount of the liabilities in the reporting entity's statement of financial position that relate to the reporting entity's variable interest in the Variable Interest Entity (VIE), where the reporting entity is not the VIE's primary beneficiary. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 50 -Paragraph 4 -Subparagraph a -URI http://asc.fasb.org/extlink&oid=108788376&loc=d3e5728-111685 + Details
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