CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions		3 Months Ended
		Mar. 31, 2020	Mar. 31, 2019
Income Statement [Abstract]
OPERATING REVENUE	[1]	$ 5,228	$ 5,427
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)	[1]	2,235	2,300
Selling, general and administrative		853	932
Depreciation and amortization		1,160	1,188
Goodwill impairment		0	6,506
Total operating expenses	[1]	4,248	10,926
OPERATING INCOME (LOSS)		980	(5,499)
OTHER (EXPENSE) INCOME
Interest expense		(449)	(523)
Other loss, net		(98)	(5)
Total other expense, net		(547)	(528)
INCOME (LOSS) BEFORE INCOME TAXES		433	(6,027)
Income tax expense		119	138
NET INCOME (LOSS)		$ 314	$ (6,165)
BASIC AND DILUTED EARNINGS (LOSS) PER COMMON SHARE
BASIC (in dollars per share)		$ 0.29	$ (5.77)
DILUTED (in dollars per share)		$ 0.29	$ (5.77)
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)		1,075,459	1,068,878
DILUTED (in shares)		1,081,754	1,068,878

[1] Reclassifications were made within certain 2019 comparative figures due to the retrospective application of an accounting policy election during the first quarter of 2020. Refer to Note 1 - Background and our Form 8-K filing dated April 30, 2020 for further information.