Debt, revolving credit facilities (Details) $ in Millions		9 Months Ended
		Sep. 30, 2016 USD ($)	Sep. 30, 2015 USD ($)	Jul. 01, 2019
TDS Revolving credit facility | TDS Parent Company
Revolving credit
Maximum borrowing capacity		$ 400
Letters of credit outstanding		1
Amount available for use		$ 399
Illustrative borrowing rate: One-month London InterBank Offered Rate ("LIBOR") plus contractual spread	[1]	2.28%
Illustrative LIBOR rate		0.53%
Contractual spread		1.75%
Commitment fees on amount available for use	[2]	0.30%
Agreement date		Jun. 15, 2016
Maturity date		Jun. 15, 2021
U.S. Cellular Revolving credit facility | U.S. Cellular
Revolving credit
Maximum borrowing capacity		$ 300
Letters of credit outstanding		16
Amount available for use		$ 284
Illustrative borrowing rate: One-month London InterBank Offered Rate ("LIBOR") plus contractual spread	[1]	2.28%
Illustrative LIBOR rate		0.53%
Contractual spread		1.75%
Commitment fees on amount available for use	[2]	0.30%
Agreement date		Jun. 15, 2016
Maturity date		Jun. 15, 2021
TDS and U.S. Cellular Revolving credit facility
Revolving credit
Interest Coverage Ratio		3.00
Leverage Ratio		3.25
Covenant compliance		TDS and U.S. Cellular believe that they were in compliance with all of the financial and other covenants and requirements set forth in their revolving credit facilities as of September 30, 2016.
TDS and U.S. Cellular Revolving credit facility | Future period
Revolving credit
Leverage Ratio				3.00
Aggregate revolving credit facilities
Revolving credit
Unused commitment fees		$ 1	$ 2
Other assets and deferred charges | Aggregate revolving credit facilities
Revolving credit
Debt issuance cost		6
Other assets and deferred charges | New revolving credit facilities
Revolving credit
Debt issuance cost		$ 4

[1] Borrowings under the revolving credit facility bear interest either at a LIBOR rate or at an alternative Base Rate as defined in the revolving credit agreement, plus an applicable margin, at TDS' or U.S. Cellular’s option. TDS and U.S. Cellular may select a borrowing period of either one, two, three or six months (or other period of twelve months or less if requested by TDS or U.S. Cellular and approved by the lenders).

[2] The revolving credit facility has commitment fees based on the unsecured senior debt ratings assigned to TDS and U.S. Cellular by certain ratings agencies.