Consolidated Statements of Income - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement [Abstract]
Revenue	$ 2,059	$ 2,033	$ 6,168	$ 6,140
Costs and Expenses:
Network access costs	678	675	2,044	2,045
Network related expenses	345	337	1,018	1,014
Depreciation and amortization	333	319	983	930
Selling, general and administrative expenses	348	348	1,078	1,061
Total Costs and Expenses	1,704	1,679	5,123	5,050
Operating Income	355	354	1,045	1,090
Other Income (Expense):
Interest income	6	1	11	3
Interest expense	(134)	(139)	(400)	(414)
Loss on modification and extinguishment of debt	0	0	(44)	(40)
Other, net	6	1	9	(14)
Total Other Expense	(122)	(137)	(424)	(465)
Income Before Income Taxes	233	217	621	625
Income Tax Expense	(76)	(74)	(215)	(198)
Net Income	$ 157	$ 143	$ 406	$ 427
Basic Earnings per Common Share
Net Income Per Share, basic (usd per share)	$ 0.43	$ 0.40	$ 1.12	$ 1.19
Weighted-Average Shares Outstanding (in thousands)	363,471	359,561	362,413	358,097
Diluted Earnings per Common Share
Net Income Per Share, diluted (usd per share)	$ 0.43	$ 0.39	$ 1.11	$ 1.18
Weighted-Average Shares Outstanding (in thousands)	365,323	361,907	364,710	361,072