CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
OPERATING ACTIVITIES
Net income	$ 1,389	$ 626	$ 878
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,936	3,916	4,189
Impairment of assets	0	13	9
Deferred income taxes	(931)	6	350
Loss on the sale of data centers and colocation business	82	0	0
Provision for uncollectible accounts	176	192	177
Net long-term debt issuance costs and premium amortization	9	2	(3)
Net loss on early retirement of debt	5	27	0
Share-based compensation	111	80	73
Changes in current assets and liabilities:
Accounts receivable	31	(266)	(132)
Accounts payable	(123)	109	(168)
Accrued income and other taxes	54	(43)	32
Other current assets and liabilities, net	(614)	92	(53)
Retirement benefits	(202)	(152)	(141)
Changes in other noncurrent assets and liabilities, net	(174)	(18)	(77)
Other, net	129	24	19
Net cash provided by operating activities	3,878	4,608	5,153
INVESTING ACTIVITIES
Payments for property, plant and equipment and capitalized software	(3,106)	(2,981)	(2,872)
Cash paid for Level 3 acquisition, net of $2.3 billion cash acquired	(7,289)	0	0
Cash paid for other acquisitions	(5)	(39)	(4)
Proceeds from sale of property and intangible assets	1,529	30	31
Other, net	0	(4)	(8)
Net cash used in investing activities	(8,871)	(2,994)	(2,853)
FINANCING ACTIVITIES
Net proceeds from issuance of long-term debt	8,398	2,161	989
Proceeds from financing obligation (Note 3)	356	0	0
Payments of long-term debt	(1,963)	(2,462)	(966)
Net proceeds from credit facility and revolving line of credit	35
Net payments on credit facility and revolving line of credit		(40)	(315)
Dividends paid	(1,453)	(1,167)	(1,198)
Repurchase of common stock and shares withheld to satisfy tax withholdings	(17)	(16)	(819)
Other, net	2	6	8
Net cash provided by (used in) financing activities	5,358	(1,518)	(2,301)
Effect of exchange rate changes on cash and cash equivalents	(2)	0	0
Net increase (decrease) in cash, cash equivalents and restricted cash	363	96	(1)
Cash, cash equivalents and restricted cash at beginning of period	224	128	129
Cash, cash equivalents and restricted cash at end of period	587	224	128
Supplemental cash flow information:
Income taxes paid, net	(392)	(397)	(63)
Interest paid (net of capitalized interest of $78, $54 and $52)	$ (1,401)	$ (1,301)	$ (1,310)