CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Income Statement [Abstract]
OPERATING REVENUE	$ 5,578	$ 5,902	$ 11,225	$ 11,847
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)	2,446	2,730	4,966	5,533
Selling, general and administrative	960	1,115	1,892	2,224
Depreciation and amortization	1,196	1,290	2,384	2,573
Goodwill impairment	0	0	6,506	0
Total operating expenses	4,602	5,135	15,748	10,330
OPERATING INCOME (LOSS)	976	767	(4,523)	1,517
OTHER (EXPENSE) INCOME
Interest expense	(518)	(546)	(1,041)	(1,081)
Other income, net	44	16	39	37
Total other expense, net	(474)	(530)	(1,002)	(1,044)
INCOME (LOSS) BEFORE INCOME TAXES	502	237	(5,525)	473
Income tax expense (benefit)	131	(55)	269	66
NET INCOME (LOSS)	$ 371	$ 292	$ (5,794)	$ 407
BASIC AND DILUTED EARNINGS (LOSS) PER COMMON SHARE
BASIC (in dollars per share)	$ 0.35	$ 0.27	$ (5.41)	$ 0.38
DILUTED (in dollars per share)	$ 0.35	$ 0.27	$ (5.41)	$ 0.38
WEIGHTED-AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)	1,071,341	1,064,711	1,070,110	1,064,663
DILUTED (in shares)	1,072,813	1,068,819	1,070,110	1,068,414