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
Retained earnings | ASC 842	$ 2				$ 2	$ 2
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
Retained earnings | ASC 842	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
Retained earnings	2,550
Retained earnings | ASC 326	(1)				(1)	(1)
Beginning balance at Dec. 31, 2019	4,210	88	1,629	(70)	2,550	4,197	13
Net income attributable to U.S. Cellular shareholders	139				139	139
Net income attributable to noncontrolling interests classified as equity	1					0	1
Repurchase of Common Shares	(23)			(23)		(23)
Incentive and compensation plans	(8)			23	(31)	(8)
Stock-based compensation awards	17		17			17
Distributions to noncontrolling interests	(1)					0	(1)
Ending balance at Jun. 30, 2020	4,334	88	1,646	(70)	2,657	4,321	13
Retained earnings | ASC 326	(1)				(1)	(1)
Beginning balance at Mar. 31, 2020	4,264	88	1,636	(92)	2,620	4,252	12
Net income attributable to U.S. Cellular shareholders	68				68	68
Net income attributable to noncontrolling interests classified as equity	1					0	1
Incentive and compensation plans	(8)			22	(30)	(8)
Stock-based compensation awards	10		10			10
Ending balance at Jun. 30, 2020	4,334	$ 88	$ 1,646	$ (70)	$ 2,657	$ 4,321	$ 13
Retained earnings	$ 2,657