CONSOLIDATED STATEMENTS OF OPERATIONS - USD ($) shares in Thousands, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Income Statement [Abstract]
OPERATING REVENUES	$ 5,323	$ 4,034	$ 4,090	$ 4,209	$ 4,289	$ 4,382	$ 4,398	$ 4,401	$ 17,656	$ 17,470	$ 17,900
OPERATING EXPENSES
Cost of services and products (exclusive of depreciation and amortization)									8,203	7,774	7,778
Selling, general and administrative									3,508	3,447	3,354
Depreciation and amortization									3,936	3,916	4,189
Total operating expenses									15,647	15,137	15,321
OPERATING INCOME	524	487	367	631	405	593	647	688	2,009	2,333	2,579
OTHER (EXPENSE) INCOME
Interest expense									(1,481)	(1,318)	(1,312)
Other income, net									12	5	49
Total other expense, net									(1,469)	(1,313)	(1,263)
INCOME BEFORE INCOME TAX EXPENSE									540	1,020	1,316
Income tax (benefit) expense									(849)	394	438
NET INCOME	$ 1,117	$ 92	$ 17	$ 163	$ 42	$ 152	$ 196	$ 236	$ 1,389	$ 626	$ 878
BASIC AND DILUTED EARNINGS PER COMMON SHARE
BASIC (in dollars per share)	$ 1.26	$ 0.17	$ 0.03	$ 0.30	$ 0.08	$ 0.28	$ 0.36	$ 0.44	$ 2.21	$ 1.16	$ 1.58
DILUTED (in dollars per share)	$ 1.26	$ 0.17	$ 0.03	$ 0.30	$ 0.08	$ 0.28	$ 0.36	$ 0.44	$ 2.21	$ 1.16	$ 1.58
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING
BASIC (in shares)									627,808	539,549	554,278
DILUTED (in shares)									628,693	540,679	555,093