Net Income Per Share Attributable To Common Stockholders (Schedule of Net Income (Loss) Reconciliation) (Details) - USD ($) shares in Millions, $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Earnings Per Share [Abstract]
Net income attributable to common stockholders	$ 756	$ 978	$ 833
Participating basic earnings	(3)	(5)	(6)
Net income (loss) attributable to common stockholders	$ 753	$ 973	$ 827
Basic and diluted weighted average common shares outstanding	167	171	170