CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Millions	Total	COMMON STOCK (represents dollars and shares)	ADDITIONAL PAID-IN CAPITAL	ACCUMULATED OTHER COMPREHENSIVE LOSS	RETAINED EARNINGS (ACCUMULATED DEFICIT)
Balance at beginning of period at Dec. 31, 2014		$ 569	$ 16,324	$ (2,017)	$ 147
Increase (Decrease) in Stockholders' Equity
Issuance of common stock to acquire Level 3, including replacement of Level 3's share-based compensation awards		0	0
Issuance of common stock through dividend reinvestment, incentive and benefit plans		2	9
Repurchase of common stock		(27)	(767)
Shares withheld to satisfy tax withholdings			(19)
Share-based compensation and other, net			77
Dividends declared			(446)		(753)
Other comprehensive income (loss)	$ 83			83
Net income	878				878
Balance at end of period at Dec. 31, 2015	14,060	544	15,178	(1,934)	272
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU 2016-09, Improvements to Employee Share-Based Payment Accounting | Restatement adjustment | Accounting Standards Update 2016-09					0
Issuance of common stock to acquire Level 3, including replacement of Level 3's share-based compensation awards		0	0
Issuance of common stock through dividend reinvestment, incentive and benefit plans		3	7
Repurchase of common stock		0	0
Shares withheld to satisfy tax withholdings			(15)
Share-based compensation and other, net			79
Dividends declared			(279)		(899)
Other comprehensive income (loss)	(183)			(183)
Net income	626				626
Balance at end of period at Dec. 31, 2016	13,399	547	14,970	(2,117)	(1)
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU 2016-09, Improvements to Employee Share-Based Payment Accounting | Restatement adjustment | Accounting Standards Update 2016-09					0
Issuance of common stock to acquire Level 3, including replacement of Level 3's share-based compensation awards		517	9,462
Issuance of common stock through dividend reinvestment, incentive and benefit plans		5	0
Repurchase of common stock		0	0
Shares withheld to satisfy tax withholdings			(20)
Share-based compensation and other, net			79
Dividends declared			(1,177)		(288)
Other comprehensive income (loss)	122			122
Net income	1,389				1,389
Balance at end of period at Dec. 31, 2017	$ 23,491	$ 1,069	$ 23,314	$ (1,995)	1,103
Increase (Decrease) in Stockholders' Equity
Cumulative effect of adoption of ASU 2016-09, Improvements to Employee Share-Based Payment Accounting | Restatement adjustment | Accounting Standards Update 2016-09					$ 3