Other Assets, Net (Schedule of Other Assets, Net) (Details) - USD ($) $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Marketable securities held in trusts(1)	$ 753	$ 642
Computer software, net of accumulated amortization of $1,249 and $1,201 at December 31, 2019 and 2018, respectively	252	261
Other intangible assets, net of accumulated amortization of $873 and $760 at December 31, 2019 and 2018, respectively	283	361
Deferred tax asset(2)	534	331
Other noncurrent assets, net	552	429
Total	2,374	2,024
Computer Software, Accumulated Amortization	1,249	1,201
Other Intangible Assets, Accumulated Amortization	$ 873	$ 760