Organization and Summary of Significant Accounting Policies (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended												12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2018	Dec. 31, 2017		Dec. 31, 2016
Organization and Summary of Significant Accounting Policies [Abstract]
Net income (loss)	$ 307	$ (29)	$ 51	$ 208	$ 334	$ 77	$ 284	$ 351	$ (210)	$ (708)	$ (593)	$ (1,132)	$ 537	$ 1,046	[1]	$ (2,643)
Mandatory convertible preferred stock dividend														108		108
Participating securities - mandatory convertible preferred stock													2	123
Net Income (Loss) Attributable to Common Stock	$ 307	$ (29)	$ 51	$ 205	$ 267	$ 43	$ 224	$ 281					$ 535	$ 815		$ (2,751)
Number of common shares: Weighted average outstanding													574,631,756	498,264,321		435,337,402
Number of common shares: Effect of issuance of non-vested restricted common stock													698,103	1,061,056
Number of common shares: Effect of issuance of non-vested performance units													1,312,949	1,478,920
Number of common shares: Weighted average and potential dilutive outstanding													576,642,808	500,804,297		435,337,402
Basic	$ 0.54	$ (0.05)	$ 0.09	$ 0.36	$ 0.53	$ 0.09	$ 0.45	$ 0.57					$ 0.93	$ 1.64		$ (6.32)
Diluted	$ 0.54	$ (0.05)	$ 0.09	$ 0.36	$ 0.53	$ 0.09	$ 0.45	$ 0.57					$ 0.93	$ 1.63		$ (6.32)

[1] In 2018 and 2017, deferred tax activity incurred in other comprehensive income was offset by a valuation allowance.