Fair Value Measurements And Disclosure (Notional Amount Of Our Outstanding Derivative Positions) (Details) - USD ($) $ in Millions	Sep. 30, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	$ 47,618	$ 47,769
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	853	3,483
Cross-Currency Swaps [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	42,792	42,192
Interest Rate Locks [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	3,500	0
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	$ 473	$ 2,094