Organization and Summary of Significant Accounting Policies (Schedule of Supplemental Disclosures of Cash Flow Information) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Organization and Summary of Significant Accounting Policies [Abstract]
Cash paid during the year for interest, net of amounts capitalized	$ 130	$ 75	$ 6
Cash received during the year for income taxes	(5)	(15)	(6)
Increase (decrease) in noncash property additions	$ 25	$ 55	$ (10)