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, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018		Dec. 31, 2017
Earnings Per Share [Line Items]
Net income									$ 891	$ 537	[1]	$ 1,046	[1]
Mandatory convertible preferred stock dividend									0	0		108
Participating securities - mandatory convertible preferred stock									0	2		123
Net Income (Loss) Attributable to Common Stock	$ 110	$ 49	$ 138	$ 594	$ 307	$ (29)	$ 51	$ 205	$ 891	$ 535		$ 815
Number of common shares:
Weighted average outstanding (in shares)									539,345,343	574,631,756		498,264,321
Weighted average and potential dilutive outstanding (in shares)									540,382,914	576,642,808		500,804,297
Basic (in dollars per share)	$ 0.20	$ 0.09	$ 0.26	$ 1.10	$ 0.54		$ 0.09	$ 0.36	$ 1.65	$ 0.93		$ 1.64
Diluted (in dollars per share)	$ 0.20	$ 0.09	$ 0.26	$ 1.10	$ 0.54	$ (0.05)	$ 0.09	$ 0.36	$ 1.65	$ 0.93		$ 1.63
Stock Options
Number of common shares:
Effect of share-based compensation (in shares)									0	0		0
Restricted Stock
Number of common shares:
Effect of share-based compensation (in shares)									361,380	698,103		1,061,056
Performance units
Number of common shares:
Effect of share-based compensation (in shares)									676,191	1,312,949		1,478,920

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