Noncontrolling Interests (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Consolidation, Less than Wholly Owned Subsidiary, Parent Ownership Interest, Change Due to Net Income Attributable to Parent and Effects of Changes, Net [Abstract]
Net income attributable to TDS shareholders	$ 78	$ 18	$ 212	$ 110
Transfers (to) from noncontrolling interests
Change in TDS' Capital in excess of par value from UScellular's issuance of UScellular shares			(38)	(23)
Change in TDS' Capital in excess of par value from UScellular's repurchases of UScellular shares			14	6
Net transfers (to) from noncontrolling interests			(24)	(17)
Changes from net income attributable to TDS shareholders and transfers (to) from noncontrolling interests			$ 188	$ 93