Financing Receivables (Details) $ in Millions		3 Months Ended	12 Months Ended
		Dec. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) agreement	Dec. 31, 2014 USD ($) agreement
Schedule of Financing Receivables [Line Items]
Financing receivable		$ 337	$ 296	$ 337
Number of Foninvemem Agreements | agreement			3
Foninvemem Agreement, collection period				10 years
Number of Foninvemem Agreements with active collections | agreement				2
ARGENTINA
Schedule of Financing Receivables [Line Items]
Financing receivable		278	$ 237	$ 278
Derivative Assets, Gross		208	292	208
Interest Income, Other		59
Embedded Derivative, Gain on Embedded Derivative		106
CAMEROON
Schedule of Financing Receivables [Line Items]
Financing receivable	[1]	44	0	44
UNITED STATES
Schedule of Financing Receivables [Line Items]
Financing receivable		0	20	0
Brazil
Schedule of Financing Receivables [Line Items]
Financing receivable		$ 15	$ 39	$ 15

[1] (1) Represents non-contingent consideration to be received in 2016 from the sale of the Cameroon businesses in 2014. Balance is classified as short-term as of December 31, 2015. See Note 23—Discontinued Operations.