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Leases - Components of Lease Income (Details) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2020 | Dec. 31, 2019
Leases |  |
Operating lease income | $ 77 | $ 74
Tower leases out of period adjustment |  |
Leases |  |
Immaterial error correction |  | During the third quarter of 2019, UScellular recorded an out-of-period adjustment attributable to 2009 through the second quarter of 2019 due to errors in the timing of recognition of revenue for certain tower leases. This out-of-period adjustment had the impact of increasing operating lease income by $5 million for the year ended December 31, 2019. UScellular determined that this adjustment was not material to any of the periods impacted.
Other service revenues | Tower leases out of period adjustment |  |
Leases |  |
Out-of-period adjustment |  | $ 5

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- Definition Amount of operating lease income from lease payments and variable lease payments paid and payable to lessor. Includes, but is not limited to, variable lease payments not included in measurement of lease receivable. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=121576215&loc=SL77919372-209981 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 842 -SubTopic 30 -Section 45 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=121561866&loc=SL77919311-209978 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 270 -SubTopic 10 -Section 50 -Paragraph 6A -URI http://asc.fasb.org/extlink&oid=121640914&loc=SL77927221-108306 + Details
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