Earnings Per Share (Schedule of Earnings Per Share) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018		Mar. 31, 2017
Earnings Per Share [Abstract]
Net income	$ 208	[1]	$ 351
Mandatory convertible preferred stock dividend			27
Participating securities - mandatory convertible preferred stock	3		43
Net Income Attributable to Common Stock	$ 205		$ 281
Number of common shares: Weighted average outstanding	571,297,804		493,068,000
Number of common shares: Issued upon assumed exercise of outstanding stock options			82,845
Number of common shares: Effect of issuance of non-vested restricted common stock	914,096		770,429
Number of common shares: Effect of issuance of non-vested performance units	1,632,559		573,721
Number of common shares: Weighted average and potential dilutive outstanding	573,844,459		494,494,995
Earnings per common share: Basic	$ 0.36		$ 0.57
Earnings per common share: Diluted	$ 0.36		$ 0.57

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