Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Earnings Per Share [Abstract]
Net income	$ 594	$ 208
Participating securities - mandatory convertible preferred stock	0	3
Net Income Attributable to Common Stock	$ 594	$ 205
Number of common shares:
Weighted average outstanding (in shares)	539,721,751	571,297,804
Issued upon assumed exercise of outstanding stock options (in shares)	0	0
Effect of issuance of non-vested restricted common stock (in shares)	665,435	914,096
Effect of issuance of non-vested performance units (in shares)	933,301	1,632,559
Weighted average and potential dilutive outstanding (in shares)	541,320,487	573,844,459
Earnings per common share:
Basic (in dollars per share)	$ 1.10	$ 0.36
Diluted (in dollars per share)	$ 1.10	$ 0.36