Acquisitions, Investments and Dispositions - Panoche Valley (Details) - Panoche Valley - California $ in Millions	1 Months Ended
	Oct. 31, 2016 USD ($) MW	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Percentage of equity interest owned	50.00%
Percentage of voting interest acquired	50.00%
Generating capacity (MW AC) | MW	240
Cash consideration	$ 28
Outstanding note payable relieved at acquisition	242
Non-utility construction work in progress	290
Other assets	22
Current liabilities	$ 14
Net assets		$ 388