Property And Equipment (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Property, Plant and Equipment [Line Items]
Depreciation expense	$ 147	$ 124	$ 111
Amortization expense on computer software and leasehold improvements	528	528	490
Computer software amortization	450	465	$ 435
Capitalized costs related to the internal development of software	$ 3,939	$ 3,226