Consolidated Statement of Changes in Equity - USD ($) $ in Millions	Total	Series A Common and Common shares	Additional paid-in capital	Treasury shares	Retained earnings	Total U.S. Cellular shareholders' equity	Noncontrolling interests
Beginning balance at Dec. 31, 2016	$ 3,645	$ 88	$ 1,522	$ (136)	$ 2,160	$ 3,634	$ 11
Net income attributable to U.S. Cellular shareholders	38				38	38
Net income attributable to noncontrolling interests classified as equity	2						2
Incentive and compensation plans				15	(15)
Stock-based compensation awards	14		14			14
Distributions to noncontrolling interests	(2)						(2)
Ending balance at Jun. 30, 2017	3,697	88	1,536	(121)	2,183	3,686	11
Beginning balance at Dec. 31, 2017	3,687	88	1,552	(120)	2,157	3,677	10
Net income attributable to U.S. Cellular shareholders	93				93	93
Net income attributable to noncontrolling interests classified as equity	1						1
Incentive and compensation plans				21	(21)
Stock-based compensation awards	17		17			17
Distributions to noncontrolling interests	(1)						(1)
Ending balance at Jun. 30, 2018	3,971	$ 88	$ 1,569	$ (99)	2,402	3,960	11
Cumulative effect of accounting change	$ 174				$ 173	$ 173	$ 1