Segments (Segment Financial Information) (Details) $ in Millions		3 Months Ended
		Jun. 30, 2016 USD ($) segments	Jun. 30, 2015 USD ($)
Segment Reporting Information [Line Items]
Document Period End Date		Jun. 30, 2016
Number of Reportable Segments | segments		2
Segment Reporting Information, Total Net Operating Revenues		$ 8,012	$ 8,027
Revenues		8,012	8,027
Segment Operating Expenses		(5,555)	(5,945)
Segment Reporting Information Operating Income or Loss		2,457	2,082
Depreciation		1,680	1,241
Amortization		(287)	(347)
Other Operating Expenses Net	[1]	129	(7)
Operating Income		361	501
Interest Expense		(615)	(542)
Other income, net		8	4
Loss (income) before income taxes		(246)	(37)
Payments to Acquire Property, Plant and Equipment Inclusive of Equipment on Lease		878	2,346
Severance and exit costs		16	13
Gain (Loss) on Contract Termination		96	0
Restructuring Charges		(18)
Pension Expense			(59)
Loss Contingency Accrual, Provision			(91)
Loss on Disposition of Property Plant Equipment		(120)	0
Wireless [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Total Net Operating Revenues		7,597	7,540
Revenues		7,597	7,540
Segment Operating Expenses		(5,157)	(5,466)
Segment Reporting Information Operating Income or Loss		2,440	2,074
Payments to Acquire Property, Plant and Equipment Inclusive of Equipment on Lease		781	2,184
Gain (Loss) on Contract Termination		(113)
Wireline [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Total Net Operating Revenues		412	483
Revenues		545	630
Segment Operating Expenses		(526)	(621)
Segment Reporting Information Operating Income or Loss		19	9
Payments to Acquire Property, Plant and Equipment Inclusive of Equipment on Lease		20	68
Impaired Assets to be Disposed of by Method Other than Sale, Amount of Impairment Loss			233
Corporate, Other And Eliminations [Member]
Segment Reporting Information [Line Items]
Segment Reporting Information, Total Net Operating Revenues		3	4
Revenues	[2]	(130)	(143)
Segment Operating Expenses		128	142
Segment Reporting Information Operating Income or Loss		(2)	(1)
Payments to Acquire Property, Plant and Equipment Inclusive of Equipment on Lease		77	94
Lease and severance [Member]
Segment Reporting Information [Line Items]
Severance and exit costs		16
Restructuring Charges			(13)
Leased devices [Member]
Segment Reporting Information [Line Items]
Restructuring Charges		(120)
Lease [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	[3]	(10)
Lease [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Restructuring Charges	[4]	(10)
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		133	147
Intersegment Eliminations [Member] | Corporate, Other And Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues		(133)	(147)
Trademarks [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)			1,900
Other Operating Income (Expense) [Member] | Wireless [Member]
Segment Reporting Information [Line Items]
Restructuring Reserve, Accrual Adjustment			41
New York sales taxes on receipts from sale of wireless services [Member]
Segment Reporting Information [Line Items]
Loss Contingency Accrual, Provision		$ (180)
Successor [Member] | 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, 2016 consists of $16 million of severance and exit costs and $113 million of contract termination costs, primarily related to the termination of our pre-existing wholesale arrangement with nTelos, as a result of the Shentel transaction. Losses totaling approximately $120 million relating to the write-off of leased devices associated with lease cancellations were excluded from Other, net and included within Wireless segment earnings. Other, net for the three-month period ended June 30, 2015 consists of $20 million of income resulting from a revision to our estimate of a previously recorded reserve, partially offset by $13 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] For the three-month period ended June 30, 2016, we recognized costs of $10 million (Wireless only).

[4] For the three-month period ended June 30, 2016, $2 million (solely attributable to Wireline) was recognized as "Cost of services" and $2 million (solely attributable to Wireless) was recognized as "Severance and exit costs." We continually refine our network strategy and evaluate other potential network initiatives to improve the overall performance of our network. Additionally, a major cost reduction initiative is underway, which may include headcount reductions, among other actions, to reduce operating expenses and improve our operating cash flows. As a result of these ongoing activities, we may incur future material charges associated with lease and access exit costs, severance, asset impairments, and accelerated depreciation, among others.

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