Business Segment Information (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020		Sep. 30, 2019	Sep. 30, 2020		Sep. 30, 2019	Dec. 31, 2019
Segment Reporting Information [Line Items]
Total operating revenues	$ 1,324		$ 1,321	$ 3,849		$ 3,840
Selling, general and administrative	415		439	1,227		1,260
Depreciation, amortization and accretion	217		237	685		697
(Gain) loss on asset disposals, net	6		6	15		5
(Gain) loss on sale of business and other exit costs, net	0		0	0		(1)
(Gain) loss on license sales and exchanges, net	0		2	0		0
Operating income	87		29	238		171
Equity in earnings of unconsolidated entities	48		44	138		129
Interest and dividend income	4		7	12		24
Gain (loss) on investments	3		0	3		0
Interest expense	(43)		(42)	(119)		(128)
Other, net	0		0	(1)		0
Income before income taxes	99		38	271		196
Income tax expense (benefit)	6		15	17		64
Net income	93		23	254		132
Depreciation, amortization and accretion	217		237	685		697
(Gain) loss on asset disposals, net	6		6	15		5
(Gain) loss on sale of business and other exit costs, net	0		0	0		(1)
(Gain) loss on license sales and exchanges, net	0		2	0		0
(Gain) loss on investments	(3)		0	(3)		0
Interest expense	43		42	119		128
Income tax expense	6		15	17		64
Adjusted EBITDA	362		325	1,087		1,025
Investments in unconsolidated entities	508		511	508		511	$ 488
Total assets	11,895	[1]	10,881	11,895	[1]	10,881	$ 10,781	[1]
Capital expenditures	310		253	849		664
Service
Segment Reporting Information [Line Items]
Total operating revenues	1,046		1,030	3,088		3,038
Cost of goods and services	321		313	919		900
Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	278		291	761		802
Cost of goods and services	278		295	765		808
UScellular
Segment Reporting Information [Line Items]
Total operating revenues	1,027		1,031	2,964		2,970
Selling, general and administrative	335		358	994		1,027
Depreciation, amortization and accretion	161		181	516		524
(Gain) loss on asset disposals, net	6		5	14		13
(Gain) loss on sale of business and other exit costs, net						(1)
(Gain) loss on license sales and exchanges, net			2
Operating income	65		20	168		115
Equity in earnings of unconsolidated entities	48		44	137		128
Interest and dividend income	2		4	6		14
Gain (loss) on investments	3			3
Interest expense	(29)		(29)	(76)		(87)
Other, net				0
Income before income taxes	89		39	238		170
Income tax expense (benefit)	4		15	11		55
Net income	85		24	227		115
Depreciation, amortization and accretion	161		181	516		524
(Gain) loss on asset disposals, net	6		5	14		13
(Gain) loss on sale of business and other exit costs, net						(1)
(Gain) loss on license sales and exchanges, net			2
(Gain) loss on investments	(3)			(3)
Interest expense	29		29	76		87
Income tax expense	4		15	11		55
Adjusted EBITDA	282		256	841		793
Investments in unconsolidated entities	467		471	467		471
Total assets	9,180		8,291	9,180		8,291
Capital expenditures	216		170	621		467
UScellular | Service
Segment Reporting Information [Line Items]
Total operating revenues	775		774	2,290		2,272
Cost of goods and services	203		199	580		568
UScellular | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	252		257	674		698
Cost of goods and services	257		266	692		724
TDS Telecom Total
Segment Reporting Information [Line Items]
Total operating revenues	247		231	728		695
Selling, general and administrative	69		67	200		193
Depreciation, amortization and accretion	49		50	152		150
(Gain) loss on asset disposals, net	0		0	1		(7)
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
Operating income	28		20	87		86
Equity in earnings of unconsolidated entities	0		0	0		0
Interest and dividend income	1		3	4		9
Gain (loss) on investments	0			0
Interest expense	1		1	3		2
Other, net				(1)
Income before income taxes	29		24	94		97
Income tax expense (benefit)	4		5	13		23
Net income	25		18	81		74
Depreciation, amortization and accretion	49		50	152		150
(Gain) loss on asset disposals, net	0		0	1		(7)
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
(Gain) loss on investments	0			0
Interest expense	(1)		(1)	(3)		(2)
Income tax expense	4		5	13		23
Adjusted EBITDA	78		73	243		238
Investments in unconsolidated entities	4		4	4		4
Total assets	2,250		2,066	2,250		2,066
Capital expenditures	92		81	221		193
TDS Telecom Total | Service
Segment Reporting Information [Line Items]
Total operating revenues	247		231	727		694
Cost of goods and services	100		94	287		274
TDS Telecom Total | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	0		0	1		1
Cost of goods and services	0		0	1		1
TDS Telecom Wireline
Segment Reporting Information [Line Items]
Total operating revenues	173		169	512		512
Selling, general and administrative	51		52	148		148
Depreciation, amortization and accretion	30		33	94		99
(Gain) loss on asset disposals, net	0		0	0		(8)
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
Operating income	23		16	73		78
Equity in earnings of unconsolidated entities	0		0	0		0
Interest and dividend income	1		3	4		8
Gain (loss) on investments	0			0
Interest expense	1		1	3		2
Other, net				(1)
Income before income taxes	24		20	79		88
Depreciation, amortization and accretion	30		33	94		99
(Gain) loss on asset disposals, net	0		0	0		(8)
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
(Gain) loss on investments	0			0
Interest expense	(1)		(1)	(3)		(2)
Adjusted EBITDA	53		52	169		177
Investments in unconsolidated entities	4		4	4		4
Total assets	1,539		1,430	1,539		1,430
Capital expenditures	74		61	171		145
TDS Telecom Wireline | Service
Segment Reporting Information [Line Items]
Total operating revenues	173		169	511		512
Cost of goods and services	69		68	197		195
TDS Telecom Wireline | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	0		0	1		1
Cost of goods and services	0		0	1		1
TDS Telecom Cable
Segment Reporting Information [Line Items]
Total operating revenues	74		62	216		184
Selling, general and administrative	18		15	52		44
Depreciation, amortization and accretion	20		17	59		51
(Gain) loss on asset disposals, net	0		0	1		1
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
Operating income	5		3	14		8
Equity in earnings of unconsolidated entities	0		0	0		0
Interest and dividend income	0		0	1		1
Gain (loss) on investments	0			0
Interest expense	0		0	0		0
Other, net				0
Income before income taxes	5		4	15		9
Depreciation, amortization and accretion	20		17	59		51
(Gain) loss on asset disposals, net	0		0	1		1
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
(Gain) loss on investments	0			0
Interest expense	0		0	0		0
Adjusted EBITDA	25		21	74		61
Investments in unconsolidated entities	0		0	0		0
Total assets	721		644	721		644
Capital expenditures	18		20	49		48
TDS Telecom Cable | Service
Segment Reporting Information [Line Items]
Total operating revenues	74		62	216		183
Cost of goods and services	31		27	91		79
TDS Telecom Cable | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	0		0	0		0
Cost of goods and services	0		0	0		0
Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Total operating revenues	50		59	157		175
Selling, general and administrative	11		14	33		40
Depreciation, amortization and accretion	7		6	17		23
(Gain) loss on asset disposals, net	0		1	0		(1)
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
Operating income	(6)		(11)	(17)		(30)
Equity in earnings of unconsolidated entities	0		0	1		1
Interest and dividend income	1		0	2		1
Gain (loss) on investments	0			0
Interest expense	(15)		(14)	(46)		(43)
Other, net				0
Income before income taxes	(19)		(25)	(61)		(71)
Income tax expense (benefit)	(2)		(5)	(7)		(14)
Net income	(17)		(19)	(54)		(57)
Depreciation, amortization and accretion	7		6	17		23
(Gain) loss on asset disposals, net	0		1	0		(1)
(Gain) loss on sale of business and other exit costs, net						0
(Gain) loss on license sales and exchanges, net			0
(Gain) loss on investments	0			0
Interest expense	15		14	46		43
Income tax expense	(2)		(5)	(7)		(14)
Adjusted EBITDA	2		(4)	3		(6)
Investments in unconsolidated entities	37		36	37		36
Total assets	465		524	465		524
Capital expenditures	2		2	7		4
Corporate, Eliminations and Other | Service
Segment Reporting Information [Line Items]
Total operating revenues	24		25	71		72
Cost of goods and services	18		20	52		58
Corporate, Eliminations and Other | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	26		34	86		103
Cost of goods and services	$ 21		$ 29	$ 72		$ 83

[1] The consolidated total assets as of September 30, 2020 and December 31, 2019, include assets held by consolidated variable interest entities (VIEs) of $1,070 million and $915 million, respectively, which are not available to be used to settle the obligations of TDS. The consolidated total liabilities as of September 30, 2020 and December 31, 2019, include certain liabilities of consolidated VIEs of $19 million and $20 million, respectively, for which the creditors of the VIEs have no recourse to the general credit of TDS. See Note 10 — Variable Interest Entities for additional information.