Business Segment (Details) - USD ($) $ in Millions		3 Months Ended			6 Months Ended
		Jun. 30, 2018		Jun. 30, 2017	Jun. 30, 2018		Jun. 30, 2017		Dec. 31, 2017
Segment Reporting Information [Line Items]
Service		$ 993		$ 992	$ 1,970		$ 1,989
Equipment and product sales		262		255	510		496
Total operating revenues		1,255		1,247	2,480		2,485
Cost of services (excluding Depreciation, amortization and accretion reported below)		300		298	587		580
Cost of equipment and products		266		287	512		557
Selling, general and administrative		417		420	813		826
Depreciation, amortization and accretion		220		211	441		422
(Gain) loss on asset disposals, net		2		6	3		10
(Gain) loss on license sales and exchanges, net		(11)		(2)	(17)		(19)
Operating income (loss)		61		27	141		109
Equity in earnings of unconsolidated entities		40		33	78		65
Interest and dividend income		6		4	11		8
Interest expense		(43)		(43)	(86)		(85)
Other, net		1		1	2		2
Income before income taxes		65		22	146		99
Income tax expense (benefit)		21		10	45		44
Net income		44		12	101		55
Depreciation, amortization and accretion		220		211	441		422
(Gain) loss on asset disposals, net		2		6	3		10
(Gain) loss on license sales and exchanges, net		(11)		(2)	(17)		(19)
Interest expense		43		43	86		85
Income tax expense		21		10	45		44
Adjusted EBITDA	[1]	319		280	659		597
Investments in unconsolidated entities		477		452	477		452		$ 453
Total assets		9,498	[2]	9,378	9,498	[2]	9,378		$ 9,295	[2]
Capital expenditures		138		134	253		230
U.S. Cellular
Segment Reporting Information [Line Items]
Service		741	[3]	740	1,465	[3]	1,486
Equipment and product sales		233	[3]	223	450	[3]	413
Total operating revenues		974	[3]	963	1,915	[3]	1,899
Cost of services (excluding Depreciation, amortization and accretion reported below)		187		189	365		364
Cost of equipment and products		240	[3]	260	459	[3]	488
Selling, general and administrative		342		351	668		691
Depreciation, amortization and accretion		159		155	317		307
(Gain) loss on asset disposals, net		1		5	2		9
(Gain) loss on license sales and exchanges, net		(11)	[3]	(2)	(17)	[3]	(19)
Operating income (loss)		56	[3]	5	121	[3]	59
Equity in earnings of unconsolidated entities		40		33	78		66
Interest and dividend income		3		2	7		5
Interest expense		(29)		(28)	(58)		(56)
Other, net					(1)		(1)
Income before income taxes		70	[3]	12	147	[3]	73
Income tax expense (benefit)		18	[3]		40	[3]	33
Net income		52	[3]	12	107	[3]	40
Depreciation, amortization and accretion		159		155	317		307
(Gain) loss on asset disposals, net		1		5	2		9
(Gain) loss on license sales and exchanges, net		(11)	[3]	(2)	(17)	[3]	(19)
Interest expense		29		28	58		56
Income tax expense		18	[3]		40	[3]	33
Adjusted EBITDA	[1]	248		198	507		426
Investments in unconsolidated entities		439		414	439		414
Total assets		7,075		7,077	7,075		7,077
Capital expenditures		86		84	155		145
TDS Telecom
Segment Reporting Information [Line Items]
Service		230	[3],[4]	231	460	[3],[4]	459
Equipment and product sales		1	[3]		1	[3]	1
Total operating revenues		230	[3],[4]	231	461	[3],[4]	459
Cost of services (excluding Depreciation, amortization and accretion reported below)		93	[4]	89	183	[4]	176
Cost of equipment and products				1	1	[3]	1
Selling, general and administrative		64	[4]	62	124	[4]	123
Depreciation, amortization and accretion		53		48	107		97
(Gain) loss on asset disposals, net		1		1	1		1
Operating income (loss)		18	[3]	31	43	[3]	61	[5]
Interest and dividend income		2		1	3		2
Interest expense					1
Other, net		1		1	1		2	[5]
Income before income taxes		21	[3]	33	48	[3]	65
Income tax expense (benefit)		5	[3],[6]	13	12	[3],[6]	25	[6]
Net income		16	[3]	20	37	[3]	40
Depreciation, amortization and accretion		53		48	107		97
(Gain) loss on asset disposals, net		1		1	1		1
Interest expense					(1)
Income tax expense		5	[3],[6]	13	12	[3],[6]	25	[6]
Adjusted EBITDA	[1]	75		82	156		164
Investments in unconsolidated entities		4		4	4		4
Total assets		1,893	[4]	1,813	1,893	[4]	1,813
Capital expenditures		46		45	87		71
TDS Telecom Wireline
Segment Reporting Information [Line Items]
Service		173	[3]	180	348	[3]	359
Equipment and product sales					1	[3]	1
Total operating revenues		174	[3]	181	349	[3]	360
Cost of services (excluding Depreciation, amortization and accretion reported below)		67		65	131		129
Cost of equipment and products				1	1	[3]	1
Selling, general and administrative		50		49	97		97
Depreciation, amortization and accretion		36		37	72		76
(Gain) loss on asset disposals, net		1			1		1
Operating income (loss)		21	[3]	28	47	[3]	56	[5]
Interest and dividend income		2		1	3		2
Interest expense					1
Other, net		1		1	1		2	[5]
Income before income taxes		24	[3]	30	52	[3]	60
Depreciation, amortization and accretion		36		37	72		76
(Gain) loss on asset disposals, net		1			1		1
Interest expense					(1)
Adjusted EBITDA	[1]	59		67	124		137
Investments in unconsolidated entities		4		4	4		4
Total assets		1,260		1,200	1,260		1,200
Capital expenditures		33		33	62		50
TDS Telecom Cable
Segment Reporting Information [Line Items]
Service		57	[3]	51	112	[3]	100
Total operating revenues		57	[3]	51	112	[3]	100
Cost of services (excluding Depreciation, amortization and accretion reported below)		27		24	52		48
Selling, general and administrative		15		13	28		25
Depreciation, amortization and accretion		18		11	35		21
(Gain) loss on asset disposals, net					1		1
Operating income (loss)		(3)	[3]	3	(4)	[3]	5
Income before income taxes		(2)	[3]	3	(4)	[3]	5
Depreciation, amortization and accretion		18		11	35		21
(Gain) loss on asset disposals, net					1		1
Adjusted EBITDA	[1]	16		14	32		27
Total assets		643		611	643		611
Capital expenditures		13		12	24		21
Corporate, Eliminations and Other
Segment Reporting Information [Line Items]
Service		22	[3]	21	45	[3]	44
Equipment and product sales		28	[3]	32	59	[3]	82
Total operating revenues		51	[3]	53	104	[3]	127
Cost of services (excluding Depreciation, amortization and accretion reported below)		20		20	39		40
Cost of equipment and products		26	[3]	26	52	[3]	68
Selling, general and administrative		11		7	21		12
Depreciation, amortization and accretion		8		8	17		18
Operating income (loss)		(13)	[3]	(9)	(23)	[3]	(11)
Equity in earnings of unconsolidated entities							(1)
Interest and dividend income		1		1	1		1
Interest expense		(14)		(15)	(29)		(29)
Other, net					2		1	[5]
Income before income taxes		(26)	[3]	(23)	(49)	[3]	(39)
Income tax expense (benefit)		(2)	[3]	(3)	(7)	[3]	(14)
Net income		(24)	[3]	(20)	(43)	[3]	(25)
Depreciation, amortization and accretion		8		8	17		18
Interest expense		14		15	29		29
Income tax expense		(2)	[3]	(3)	(7)	[3]	(14)
Adjusted EBITDA		(4)	[1]		(4)		7	[1]
Investments in unconsolidated entities		34		34	34		34
Total assets		530		488	530		488
Capital expenditures		$ 6		$ 5	$ 11		$ 14

[1] Adjusted earnings before interest, taxes, depreciation, amortization and accretion (“Adjusted EBITDA”) is a segment measure reported to the chief operating decision maker for purposes of making decisions about allocating resources to the segments and assessing their performance. Adjusted EBITDA is defined as net income, adjusted for the items set forth in the reconciliation above. TDS believes Adjusted EBITDA is a useful measure of TDS’ operating results before significant recurring non-cash charges, gains and losses, and other items as presented above as they provide additional relevant and useful information to investors and other users of TDS' financial data in evaluating the effectiveness of its operations and underlying business trends in a manner that is consistent with management's evaluation of business performance.

[2] The consolidated total assets as of June 30, 2018 and December 31, 2017, include assets held by consolidated variable interest entities (VIEs) of $793 million and $765 million, respectively, which are not available to be used to settle the obligations of TDS. The consolidated total liabilities as of June 30, 2018 and December 31, 2017, include certain liabilities of consolidated VIEs of $17 million and $21 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.

[3] As of January 1, 2018, TDS adopted ASU 2014-09 using a modified retrospective approach. Under this method, the new accounting standard is applied only to the most recent period presented. As a result, 2018 amounts include the impacts of ASU 2014-09, but 2017 amounts remain as previously reported, except as specifically stated. See Note 2 - Revenue Recognition for additional information.

[4] TDS Telecom Total includes eliminations between the Wireline and Cable segments.

[5] ASU 2017-07, regarding net periodic pension cost and net periodic postretirement benefit cost was adopted as of January 1, 2018, and applied retrospectively. All prior year numbers have been recast to conform to this standard.

[6] Income tax expense (benefit) is not provided at the individual segment level for Wireline and Cable. TDS calculates income tax expense for "TDS Telecom Total".