Sale Of Equipment Installment Receivables (Finance Receivables Repurchased) (Details) - Finance Receivables [Member] - USD ($) $ in Millions		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Changes In Other Assets [Line Items]
Fair value of repurchased receivables		$ 0	$ 377
Carrying value of deferred purchase price		0	339
Gain (Loss) on repurchases	[1]	$ 0	$ 38

[1] These gains (losses) are included in “Selling, general and administrative” in the consolidated statements of income.