Revenue Recognition - Consolidated Balance Sheet (Details) - USD ($) $ in Millions		Sep. 30, 2018	Dec. 31, 2017	Sep. 30, 2017	Dec. 31, 2016
Accounts receivable
Customers and agents, less allowances		$ 845	$ 775
Prepaid expenses		62	79
Other current assets		20	21
Total current assets		1,864	1,483
Licenses		2,189	2,223
Investments in unconsolidated entities		461	415
Other assets and deferred charges		546	390
Total assets	[1]	7,228	6,841
Customer deposits and deferred revenues		145	185
Accrued taxes		52	56
Other current liabilities		83	90
Total current liabilities		689	733
Deferred income tax liability, net		510	461
Other deferred liabilities and credits		386	337
Retained earnings		2,430	2,157
Total U.S. Cellular shareholders' equity		4,012	3,677
Noncontrolling interests		11	10
Total equity		4,023	3,687	$ 3,406	$ 3,645
Total liabilities and equity	[1]	7,228	$ 6,841
Results under prior accounting standards
Accounts receivable
Customers and agents, less allowances		786
Prepaid expenses		78
Other current assets		17
Total current assets		1,818
Licenses		2,188
Investments in unconsolidated entities		446
Other assets and deferred charges		393
Total assets		7,013
Customer deposits and deferred revenues		157
Accrued taxes		55
Other current liabilities		80
Total current liabilities		701
Deferred income tax liability, net		459
Other deferred liabilities and credits		371
Retained earnings		2,270
Total U.S. Cellular shareholders' equity		3,852
Noncontrolling interests		10
Total equity		3,862
Total liabilities and equity		7,013
Adjustment | ASU 2014-09
Accounts receivable
Customers and agents, less allowances		59
Prepaid expenses		(16)
Other current assets		3
Total current assets		46
Licenses		1
Investments in unconsolidated entities		15
Other assets and deferred charges		153
Total assets		215
Customer deposits and deferred revenues		(12)
Accrued taxes		(3)
Other current liabilities		3
Total current liabilities		(12)
Deferred income tax liability, net		51
Other deferred liabilities and credits		15
Retained earnings		160
Total U.S. Cellular shareholders' equity		160
Noncontrolling interests		1
Total equity		161
Total liabilities and equity		$ 215

[1] The consolidated total assets as of September 30, 2018 and December 31, 2017, include assets held by consolidated variable interest entities (VIEs) of $851 million and $785 million, respectively, which are not available to be used to settle the obligations of U.S. Cellular. The consolidated total liabilities as of September 30, 2018 and December 31, 2017, include certain liabilities of consolidated VIEs of $20 million and $24 million, respectively, for which the creditors of the VIEs have no recourse to the general credit of U.S. Cellular. See Note 10 — Variable Interest Entities for additional information.