Unaudited Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Selected Quarterly Financial Information [Abstract]
Revenue	$ 2,032	$ 2,033	$ 2,056	$ 2,051	$ 2,053	$ 2,062	$ 2,061	$ 2,053	$ 8,172	$ 8,229	$ 6,777
Network Access Costs	680	675	676	694	708	706	696	723	2,725	2,833	2,529
Network Related Expenses	332	337	339	338	344	369	363	356	1,346	1,432	1,246
Depreciation and Amortization	320	319	310	301	294	296	288	288	1,250	1,166	808
Selling, General and Administrative Expenses	346	348	357	356	369	364	364	370	1,407	1,467	1,181
Total Costs and Expenses	1,678	1,679	1,682	1,689	1,715	1,735	1,711	1,737	6,728	6,898	5,764
Operating Income (Loss)	354	354	374	362	338	327	350	316	1,444	1,331	1,013
Interest Income	1	1	1	1	0	0	0	1	4	1	1
Interest Expense	(132)	(139)	(140)	(135)	(152)	(145)	(165)	(180)	(546)	(642)	(654)
Loss on modification and extinguishment of debt	0	0	(40)	0	(55)	0	(163)	0	(40)	(218)	(53)
Venezuela deconsolidation charge	0	0	0	0	0	(171)	0	0	0	(171)	0
Other, net	(6)	1	(5)	(10)	3	6	(17)	(10)	(20)	(18)	(69)
Total Other Expense	(137)	(137)	(184)	(144)	(204)	(310)	(345)	(189)	(602)	(1,048)	(775)
Income (Loss) Before Income Taxes	217	217	190	218	134	17	5	127	842	283	238
Income Tax Expense (Benefit)	(33)	74	34	90	(3,189)	16	18	5	165	(3,150)	(76)
Net Income	$ 250	$ 143	$ 156	$ 128	$ 3,323	$ 1	$ (13)	$ 122	$ 677	$ 3,433	$ 314
Net Income (Loss) Per Share -Basic	$ 0.70	$ 0.40	$ 0.44	$ 0.36	$ 9.33	$ 0.00	$ (0.04)	$ 0.35	$ 1.89	$ 9.71	$ 1.23
Net Income (Loss) Per Share - Diluted	$ 0.69	$ 0.39	$ 0.43	$ 0.36	$ 9.24	$ 0.00	$ (0.04)	$ 0.35	$ 1.87	$ 9.58	$ 1.21
Recognized Income Tax Benefit	$ (16)		$ 0		$ (3,300)
Debt instrument, stated interest rate (as a percent)	7.00%								7.00%
Senior Notes due 2020 (8.625%)
Selected Quarterly Financial Information [Abstract]
Loss on modification and extinguishment of debt					(55)
Debt instrument, stated interest rate (as a percent)	8.625%								8.625%
Senior Notes due 2019 (9.375%)
Selected Quarterly Financial Information [Abstract]
Loss on modification and extinguishment of debt			(36)						$ (36)
Debt instrument, stated interest rate (as a percent)	9.375%								9.375%
Senior Notes due 2019 (8.125%)
Selected Quarterly Financial Information [Abstract]
Loss on modification and extinguishment of debt			(82)
Debt instrument, stated interest rate (as a percent)	8.125%								8.125%
Senior Notes due 2019 (8.875%)
Selected Quarterly Financial Information [Abstract]
Loss on modification and extinguishment of debt			(18)
Debt instrument, stated interest rate (as a percent)	8.875%								8.875%
Tranche B 2022 Term Loans
Selected Quarterly Financial Information [Abstract]
Loss on modification and extinguishment of debt			$ 27
BRAZIL
Selected Quarterly Financial Information [Abstract]
Recognized Income Tax Benefit	$ 35
U.S. Internal Revenue Service (IRS)
Selected Quarterly Financial Information [Abstract]
Recognized Income Tax Benefit	$ 110				$ (3,300)