CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Income Statement [Abstract]
OPERATING REVENUE	$ 5,606	$ 5,818	$ 16,831	$ 17,665
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)	2,590	2,672	7,556	8,205
Selling, general and administrative	831	967	2,723	3,191
Depreciation and amortization	1,235	1,285	3,619	3,858
Goodwill impairment	0	0	6,506	0
Total operating expenses	4,656	4,924	20,404	15,254
OPERATING INCOME (LOSS)	950	894	(3,573)	2,411
OTHER (EXPENSE) INCOME
Interest expense	(496)	(557)	(1,537)	(1,638)
Other (loss) income, net	(44)	(8)	(5)	29
Total other expense, net	(540)	(565)	(1,542)	(1,609)
INCOME (LOSS) BEFORE INCOME TAXES	410	329	(5,115)	802
Income tax expense	108	57	377	123
NET INCOME (LOSS)	$ 302	$ 272	$ (5,492)	$ 679
BASIC AND DILUTED EARNINGS (LOSS) PER COMMON SHARE
BASIC (in dollars per share)	$ 0.28	$ 0.25	$ (5.13)	$ 0.64
DILUTED (in dollars per share)	$ 0.28	$ 0.25	$ (5.13)	$ 0.63
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)	1,072,543	1,066,904	1,070,921	1,065,410
DILUTED (in shares)	1,074,790	1,072,351	1,070,921	1,069,726