Aggregate dividends declared during the period for each share of common stock outstanding.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-Section S99
-Paragraph 1
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Date the dividend to be paid was declared, in CCYY-MM-DD format.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 50
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Amount of distribution received from equity method investee for return on investment, classified as operating activities. Excludes distribution for return of investment, classified as investing activities.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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-Section 45
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Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
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Subsequent Events (Details) - Enable Midstream Partners [Member] - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
	May 01, 2018	Mar. 31, 2018	Mar. 31, 2017
Subsequent Event [Line Items]
Expected cash distribution from equity method investment		$ 74	$ 74
Subsequent Event [Member]
Subsequent Event [Line Items]
Dividends payable, date declared	May 01, 2018
Quarterly cash distribution per unit declared	$ 0.318
Expected cash distribution from equity method investment	$ 74