Business Segment Information (Details) - USD ($) $ in Millions	3 Months Ended			6 Months Ended
	Jun. 30, 2021		Jun. 30, 2020	Jun. 30, 2021		Jun. 30, 2020	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total operating revenues	$ 1,311		$ 1,263	$ 2,629		$ 2,524
Selling, general and administrative	416		398	804		809
Depreciation, amortization and accretion	234		236	457		470
(Gain) loss on asset disposals, net	3		4	8		8
(Gain) loss on sale of business and other exit costs, net	0		0	(1)		0
Operating income	58		78	168		151
Equity in earnings of unconsolidated entities	48		44	90		90
Interest and dividend income	3		2	6		8
Interest expense	(86)		(38)	(138)		(75)
Other, net	0		0	(1)		(1)
Income before income taxes	23		86	125		173
Income tax expense (benefit)	(11)		8	20		12
Net income	34		78	105		161
Depreciation, amortization and accretion	234		236	457		470
(Gain) loss on asset disposals, net	3		4	8		8
(Gain) loss on sale of business and other exit costs, net	0		0	(1)		0
Interest expense	86		38	138		75
Income tax expense (benefit)	(11)		8	20		12
Adjusted EBITDA	346		364	727		726
Investments in unconsolidated entities	487		486	487		486	$ 477
Total assets	12,780	[1]	11,161	12,780	[1]	11,161	$ 12,525	[1]
Capital expenditures	250		247	446		539
Service
Segment Reporting Information [Line Items]
Total operating revenues	1,049		1,016	2,091		2,042
Cost of goods and services	324		306	623		599
Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	262		247	538		482
Cost of goods and services	276		241	570		487
UScellular
Segment Reporting Information [Line Items]
Total operating revenues	1,014		973	2,037		1,937
Selling, general and administrative	334		323	639		659
Depreciation, amortization and accretion	180		178	350		354
(Gain) loss on asset disposals, net	2		4	7		8
(Gain) loss on sale of business and other exit costs, net				(1)
Operating income	36		53	120		104
Equity in earnings of unconsolidated entities	47		44	88		89
Interest and dividend income	2		1	3		5
Interest expense	(60)		(25)	(97)		(49)
Other, net				0		0
Income before income taxes	25		73	114		149
Income tax expense (benefit)	(10)		4	17		8
Net income	35		69	97		141
Depreciation, amortization and accretion	180		178	350		354
(Gain) loss on asset disposals, net	2		4	7		8
(Gain) loss on sale of business and other exit costs, net				(1)
Interest expense	60		25	97		49
Income tax expense (benefit)	(10)		4	17		8
Adjusted EBITDA	267		280	567		560
Investments in unconsolidated entities	445		445	445		445
Total assets	9,920		8,500	9,920		8,500
Capital expenditures	148		168	273		405
UScellular | Service
Segment Reporting Information [Line Items]
Total operating revenues	774		753	1,545		1,515
Cost of goods and services	204		197	389		377
UScellular | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	240		220	492		422
Cost of goods and services	258		218	533		435
TDS Telecom
Segment Reporting Information [Line Items]
Total operating revenues	252		241	501		481
Selling, general and administrative	73		66	143		130
Depreciation, amortization and accretion	49		51	98		103
(Gain) loss on asset disposals, net	1		0	1		0
(Gain) loss on sale of business and other exit costs, net				0
Operating income	28		31	60		59
Equity in earnings of unconsolidated entities	0		0	0		0
Interest and dividend income	0		1	0		4
Interest expense	1		1	2		2
Other, net				0		(1)
Income before income taxes	29		33	62		64
Income tax expense (benefit)	7		5	15		8
Net income	22		28	46		56
Depreciation, amortization and accretion	49		51	98		103
(Gain) loss on asset disposals, net	1		0	1		0
(Gain) loss on sale of business and other exit costs, net				0
Interest expense	(1)		(1)	(2)		(2)
Income tax expense (benefit)	7		5	15		8
Adjusted EBITDA	78		83	158		165
Investments in unconsolidated entities	4		4	4		4
Total assets	2,433		2,210	2,433		2,210
Capital expenditures	99		75	169		128
TDS Telecom | Service
Segment Reporting Information [Line Items]
Total operating revenues	251		240	500		480
Cost of goods and services	101		92	199		188
TDS Telecom | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	0		0	1		1
Cost of goods and services	0		0	0		0
Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Total operating revenues	45		49	91		106
Selling, general and administrative	9		9	22		20
Depreciation, amortization and accretion	5		7	9		13
(Gain) loss on asset disposals, net	0		0	0		0
(Gain) loss on sale of business and other exit costs, net				0
Operating income	(6)		(6)	(12)		(12)
Equity in earnings of unconsolidated entities	1		0	2		1
Interest and dividend income	1		0	3		(1)
Interest expense	(27)		(14)	(43)		(28)
Other, net				(1)		0
Income before income taxes	(31)		(20)	(51)		(40)
Income tax expense (benefit)	(8)		(1)	(12)		(4)
Net income	(23)		(19)	(38)		(36)
Depreciation, amortization and accretion	5		7	9		13
(Gain) loss on asset disposals, net	0		0	0		0
(Gain) loss on sale of business and other exit costs, net				0
Interest expense	27		14	43		28
Income tax expense (benefit)	(8)		(1)	(12)		(4)
Adjusted EBITDA	1		1	2		1
Investments in unconsolidated entities	38		37	38		37
Total assets	427		451	427		451
Capital expenditures	3		4	4		6
Corporate, Eliminations and Other | Service
Segment Reporting Information [Line Items]
Total operating revenues	24		23	46		47
Cost of goods and services	19		17	35		34
Corporate, Eliminations and Other | Equipment and product sales
Segment Reporting Information [Line Items]
Total operating revenues	22		27	45		59
Cost of goods and services	$ 18		$ 23	$ 37		$ 52

[1] The consolidated total assets as of June 30, 2021 and December 31, 2020, include assets held by consolidated variable interest entities (VIEs) of $1,240 million and $1,042 million, respectively, which are not available to be used to settle the obligations of TDS. The consolidated total liabilities as of June 30, 2021 and December 31, 2020, include certain liabilities of consolidated VIEs of $17 million and $18 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.