Equipment Installment Plans (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015	Dec. 31, 2015
Equipment installment plans
Guarantee liability		$ 66		$ 93
Imputed interest rate		10.20%		9.70%
Equipment installment plans out-of-period adjustment
Equipment installment plans
Out-of-period adjustment description		U.S. Cellular recorded out-of-period adjustments during the six months ended June 30, 2015 due to errors related to equipment installment plan transactions that were attributable to 2014. U.S. Cellular determined that these adjustments were not material to the quarterly periods or the annual results for 2015. These equipment installment plan adjustments had the impact of reducing Equipment sales revenues by $6 million for both the three and six months ended June 30, 2015, and Income before income taxes by $5 million and $6 million, for the three and six months ended June 30, 2015, respectively.
Equipment sales revenues | Equipment installment plans out-of-period adjustment
Equipment installment plans
Out-of-period adjustment	$ 6		$ 6
Income before income taxes | Equipment installment plans out-of-period adjustment
Equipment installment plans
Out-of-period adjustment	$ 5		$ 6
Short-term
Equipment installment plan receivables
Unbilled equipment installment plan receivables, gross		$ 314		$ 279
Unbilled deferred interest		(28)		(21)
Unbilled allowance for credit losses		(19)		(14)
Unbilled equipment installment plan receivables, net		267		244
Long-term
Equipment installment plan receivables
Unbilled equipment installment plan receivables, gross		127		76
Unbilled deferred interest		(6)		(2)
Unbilled allowance for credit losses		(10)		(6)
Unbilled equipment installment plan receivables, net		$ 111		$ 68