Acquisitions Acquistions (Details) - USD ($) $ in Millions	3 Months Ended				12 Months Ended
	Mar. 31, 2020	Dec. 31, 2018	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017	Nov. 01, 2018	Mar. 31, 2018
Business Acquisition [Line Items]
Liquidation Basis of Accounting, Remeasurement, Gain (Loss) on Asset								$ 0
Project Financing Disbursed					$ 0	$ 119		$ 0
Distributed Energy [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Net of Cash Acquired						$ 23
Business Combination, Ownership Percentage in Acquiree		100.00%				100.00%
Business Combination, Equity Interest in Acquiree, Remeasurement Gain (Loss)		$ 5				$ (5)
Alto Sertao II [Member]
Business Acquisition [Line Items]
Business Combination, Consideration Transferred				$ 179
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Liabilities				346
Business Combination, Contingent Consideration, Liability										$ 18
Payments to Acquire Businesses, Net of Cash Acquired				$ 143
Payment for Contingent Consideration Liability, Financing Activities			$ 12
Na Pua Makani Power Partners [Member]
Business Acquisition [Line Items]
Business Acquisition, Percentage of Voting Interests Acquired									100.00%
Business Combination, Consideration Transferred		11				53
Business Combination, Contingent Consideration		$ 5				48
Liquidation Basis of Accounting, Remeasurement, Gain (Loss) on Asset					0	32	[1]
Guaimbe Solar Complex [Member]
Business Acquisition [Line Items]
Project Financing Disbursed						$ 119
Asset acquisition, additional cash paid			33
Asset Acquisition, Consideration Transferred			$ 152
Los Cururos [Member]
Business Acquisition [Line Items]
Asset Acquisition, Consideration Transferred					$ 143
Subsequent Event [Member] | Los Cururos [Member]
Business Acquisition [Line Items]
Payments to Acquire Businesses, Gross	$ 5

[1] Related to the amendment of the Oahu purchase agreement. See Note 26 —Acquisitions for further information.