Segments (Segment Financial Information) (Details) $ in Millions		3 Months Ended
		Jun. 30, 2015 USD ($) segments	Jun. 30, 2014 USD ($)
Segment Reporting Information [Line Items]
Number of Reportable Segments | segments		2
Segment Reporting Information, Total Net Operating Revenues		$ 8,027	$ 8,789
Revenues		8,027	8,789
Segment Operating Expenses		(5,945)	(6,962)
Segment Reporting Information Operating Income or Loss		2,082	1,827
Depreciation		1,241	868
Amortization		(347)	(413)
Other, net	[1]	7	(27)
Operating Income		501	519
Interest Expense		(542)	(512)
Other income, net		4	1
Loss (income) before income taxes		(37)	8
Capital Expenditures - network and others		1,802	1,246
Severance and exit costs			27
Restructuring Charges		7	(27)
Wireless [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Total Net Operating Revenues		7,540	8,193
Revenues		7,540	8,193
Segment Operating Expenses		5,466	6,400
Segment Reporting Information Operating Income or Loss		2,074	1,793
Capital Expenditures - network and others		1,640	1,120
Wireline [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Total Net Operating Revenues		483	593
Revenues		630	746
Segment Operating Expenses		621	711
Segment Reporting Information Operating Income or Loss		9	35
Capital Expenditures - network and others		68	59
Corporate, Other And Eliminations [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Total Net Operating Revenues		4	3
Revenues	[2]	(143)	(150)
Segment Operating Expenses		(142)	(149)
Segment Reporting Information Operating Income or Loss		(1)	(1)
Capital Expenditures - network and others		94	67
Lease and severance [Member]
Segment Reporting Information [Line Items]
Severance and exit costs		13
Lease [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	[3]	15
Lease [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	[4]	(5)
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues	[5]	0	0
Intersegment Eliminations [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Revenues		0	0
Intersegment Eliminations [Member] | Wireline [Member]
Segment Reporting Information [Line Items]
Revenues		147	153
Intersegment Eliminations [Member] | Corporate, Other And Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(147)	$ (153)
Other Operating Income (Expense) [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Restructuring Reserve, Accrual Adjustment		$ 20

[1] Other, net for the three-month period ended June 30, 2015 consists of $20 million release of liability reserves associated with the May 2013 U.S. Cellular asset acquisition, partially offset by $13 million of severance and exit costs. Other, net for the three-month period ended June 30, 2014 consists of $27 million of severance and exit costs,

[2] Revenues eliminated in consolidation consist primarily of wireline services provided to the Wireless segment for resale to or use by wireless subscribers.

[3] In addition to the $20 million income (Wireless only) related to U.S. Cellular, we recognized costs of $5 million (Wireless only) for the three-month period ended June 30, 2015 included in "Other, net" on the consolidated statements of comprehensive (loss) income.

[4] For the three-month period ended June 30, 2015, we recognized costs of $1 million (Wireless only) included in "Other, net" on the consolidated statements of comprehensive (loss) income.

[5] Inter-segment revenues consist primarily of wireline services provided to the Wireless segment for resale to, or use by, wireless subscribers.