Fair Value Measurements And Disclosure (Notional Amount Of Our Outstanding Derivative Positions) (Details) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	$ 45,063	$ 47,769
Interest Rate Swaps [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	1,633	3,483
Cross-Currency Swaps [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	42,192	42,192
Foreign Exchange Contracts [Member]
Derivative [Line Items]
Notional Amount of Outstanding Derivative Positions	$ 1,238	$ 2,094