CONSOLIDATED STATEMENTS OF OPERATIONS (UNAUDITED) - USD ($) shares in Thousands, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Income Statement [Abstract]
OPERATING REVENUE	$ 3,641	$ 4,390	$ 11,040	$ 13,678
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)	1,850	1,999	5,407	6,042
Selling, general and administrative	791	792	2,302	2,407
Gain on sale of business	0	(593)	0	(593)
Loss on disposal group held for sale	22	0	112	0
Depreciation and amortization	755	808	2,234	2,443
Goodwill impairment	0	0	8,793	0
Total operating expenses	3,418	3,006	18,848	10,299
OPERATING INCOME (LOSS)	223	1,384	(7,808)	3,379
OTHER EXPENSE
Interest expense	(295)	(363)	(868)	(1,052)
Net gain on early retirement of debt (Note 6)	0	9	618	9
Other expense, net	(13)	(93)	(37)	(145)
Total other expense, net	(308)	(447)	(287)	(1,188)
(LOSS) INCOME BEFORE INCOME TAXES	(85)	937	(8,095)	2,191
Income tax (benefit) expense	(7)	359	208	670
NET (LOSS) INCOME	$ (78)	$ 578	$ (8,303)	$ 1,521
Earnings Per Share [Abstract]
BASIC (in dollars per share)	$ (0.08)	$ 0.57	$ (8.45)	$ 1.50
DILUTED (in dollars per share)	$ (0.08)	$ 0.57	$ (8.45)	$ 1.50
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)	983,550	1,013,124	982,853	1,011,498
DILUTED (in shares)	983,550	1,017,013	982,853	1,016,281