CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
OPERATING ACTIVITIES
Net income (loss)	$ 878	$ 772	$ (239)
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	4,189	4,428	4,541
Impairment of goodwill (Note 2)	0	0	1,092
Impairment of assets	9	32	0
Deferred income taxes	350	291	391
Provision for uncollectible accounts	177	159	152
Gain on sale of intangible assets	0	0	(32)
Net long-term debt issuance costs and premium amortization	(3)	(21)	(46)
Net gain on early retirement of debt	0	0	(10)
Share-based compensation	73	79	71
Changes in current assets and liabilities:
Accounts receivable	(132)	(163)	(212)
Accounts payable	(168)	70	(76)
Accrued income and other taxes	32	(84)	28
Other current assets and liabilities, net	(53)	(270)	263
Retirement benefits	(141)	(184)	(342)
Changes in other noncurrent assets and liabilities, net	(78)	99	8
Other, net	19	(20)	(30)
Net cash provided by operating activities	5,152	5,188	5,559
INVESTING ACTIVITIES
Payments for property, plant and equipment and capitalized software	(2,872)	(3,047)	(3,048)
Cash paid for acquisitions	4	93	160
Proceeds from sale of property and intangible assets	31	63	80
Other, net	(8)	0	(20)
Net cash used in investing activities	(2,853)	(3,077)	(3,148)
FINANCING ACTIVITIES
Net proceeds from issuance of long-term debt	989	483	2,481
Repayments of long-term debt	(966)	(800)	(2,010)
Net payments on credit facility and revolving line of credit	(315)	(4)	(95)
Early retirement of debt costs	(1)	0	(31)
Dividends paid	(1,198)	(1,228)	(1,301)
Net proceeds from issuance of common stock	11	50	73
Repurchase of common stock	(819)	(650)	(1,586)
Other, net	(2)	(2)	15
Net cash used in financing activities	(2,301)	(2,151)	(2,454)
Net decrease in cash and cash equivalents	(2)	(40)	(43)
Cash and cash equivalents at beginning of period	128	168	211
Cash and cash equivalents at end of period	126	128	168
Supplemental cash flow information:
Income taxes paid, net	(63)	(27)	(48)
Interest paid (net of capitalized interest of $52, $47 and $41)	$ (1,310)	$ (1,338)	$ (1,333)