Acquisitions and Dispositions - Southern Company (Details) - Scenario, Forecast - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Jun. 28, 2019
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock purchase agreement, contract termination fees		$ 100
700 Universe, LLC | Minimum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock purchase agreement, contract termination fees		100
700 Universe, LLC | Maximum
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Stock purchase agreement, contract termination fees		$ 200
Disposal Group, Disposed of by Sale, Not Discontinued Operations | GULF POWER CO
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Proceeds from divestiture of businesses, net of cash divested	$ 5,750
Amount of indebtedness assumed at closing	$ 1,300