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
Cumulative effect of accounting change	$ 174				$ 173	$ 173	$ 1
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					0	1
Incentive and compensation plans	0			21	(21)	0
Stock-based compensation awards	17		17			17
Distributions to noncontrolling interests	(1)					0	(1)
Ending balance at Jun. 30, 2018	3,971	88	1,569	(99)	2,402	3,960	11
Cumulative effect of accounting change	(2)				(2)	(2)
Beginning balance at Mar. 31, 2018	3,918	88	1,560	(116)	2,375	3,907	11
Net income attributable to U.S. Cellular shareholders	49				49	49
Net income attributable to noncontrolling interests classified as equity	1					0	1
Incentive and compensation plans	(3)			17	(20)	(3)
Stock-based compensation awards	9		9			9
Distributions to noncontrolling interests	(1)					0	(1)
Ending balance at Jun. 30, 2018	3,971	88	1,569	(99)	2,402	3,960	11
Beginning balance at Dec. 31, 2018	4,067	88	1,590	(65)	2,444	4,057	10
Net income attributable to U.S. Cellular shareholders	86				86	86
Net income attributable to noncontrolling interests classified as equity	5					0	5
Incentive and compensation plans	(8)			15	(23)	(8)
Stock-based compensation awards	25		25			25
Distributions to noncontrolling interests	(2)					0	(2)
Ending balance at Jun. 30, 2019	4,175	88	1,615	(50)	2,509	4,162	13
Cumulative effect of accounting change	2				2	2
Beginning balance at Mar. 31, 2019	4,134	88	1,599	(63)	2,497	4,121	13
Net income attributable to U.S. Cellular shareholders	31				31	31
Net income attributable to noncontrolling interests classified as equity	1					0	1
Incentive and compensation plans	(8)			13	(21)	(8)
Stock-based compensation awards	16		16			16
Distributions to noncontrolling interests	(1)					0	(1)
Ending balance at Jun. 30, 2019	$ 4,175	$ 88	$ 1,615	$ (50)	$ 2,509	$ 4,162	$ 13