Acquisitions, Divestitures and Exchanges, acquisitions (Details) $ in Millions	9 Months Ended	12 Months Ended
	Sep. 30, 2015 USD ($)	Dec. 31, 2014 USD ($)
Acquisitions, divestitures and exchanges
Total winning bid	$ 338.3
U.S. Cellular | License Acquisitions | Auction 97
Acquisitions, divestitures and exchanges
Description of acquired entity	An FCC auction of AWS-3 spectrum licenses (“Auction 97”) ended in January 2015.  U.S. Cellular participated in Auction 97 indirectly through its limited partnership interest in Advantage Spectrum L.P. (“Advantage Spectrum”). Advantage Spectrum was the provisional winning bidder for 124 licenses for an aggregate winning bid of $338.3 million, after its designated entity discount of 25%.  Advantage Spectrum’s bid amount, less the initial deposit amount of $60.0 million paid in 2014, was paid to the FCC in March 2015.  These licenses have not yet been granted by the FCC.  See Note 10 — Variable Interest Entities for additional information.
Federal Communications Commission deposit		$ 60.0
Licenses won	124
Total winning bid	$ 338.3
Designated entity auction discount	25.00%