Revenue Recognition, Consolidated Statement Of Operations (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating revenues
Service	$ 724	$ 746
Equipment sales	218	190
Total operating revenues	942	936
Cost of equipment sold	219	228
(Gain) loss on license sales and exchanges, net	(7)	(17)
Total operating expenses	877	882
Operating income (loss)	65	54
Income (loss) before income taxes	77	61
Income tax expense (benefit)	22	33
Net income (loss)	55	28
Net income (loss) attributable to U.S. Cellular shareholders	$ 45	$ 26
Basic earnings (loss) per share attributable to U.S. Cellular shareholders	$ 0.52	$ 0.31
Diluted earnings (loss) per share attributable to U.S. Cellular shareholders	$ 0.52	$ 0.31
Results under prior accounting standards
Operating revenues
Service	$ 754
Equipment sales	198
Total operating revenues	952
Cost of equipment sold	222
(Gain) loss on license sales and exchanges, net	(6)
Total operating expenses	882
Operating income (loss)	70
Income (loss) before income taxes	82
Income tax expense (benefit)	24
Net income (loss)	58
Net income (loss) attributable to U.S. Cellular shareholders	$ 48
Basic earnings (loss) per share attributable to U.S. Cellular shareholders	$ 0.56
Diluted earnings (loss) per share attributable to U.S. Cellular shareholders	$ 0.56
Adjustment
Operating revenues
Service	$ (30)
Equipment sales	20
Total operating revenues	(10)
Cost of equipment sold	(3)
(Gain) loss on license sales and exchanges, net	(1)
Total operating expenses	(5)
Operating income (loss)	(5)
Income (loss) before income taxes	(5)
Income tax expense (benefit)	(2)
Net income (loss)	(3)
Net income (loss) attributable to U.S. Cellular shareholders	$ (3)
Basic earnings (loss) per share attributable to U.S. Cellular shareholders	$ (0.04)
Diluted earnings (loss) per share attributable to U.S. Cellular shareholders	$ (0.04)