Severance and Exit Costs (Schedule of Severance and Exit Costs Liability) (Details) - Successor [Member] - USD ($) $ in Millions		12 Months Ended
		Mar. 31, 2016		Mar. 31, 2015
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning		$ 454		$ 971
Severance costs, beginning		119		197
Restructuring charges		391		263
Severance costs		216	[1]	253	[2]
Restructuring reserve, settled with cash		(320)		(780)
Payments for postemployment benefits		(185)		(331)
Restructuring reserve, end		525		454
Severance costs, end		150		119
Lease [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning		291		650
Restructuring charges excluding US Cellular gain		176		13
Restructuring charges		156	[3]	(28)	[4]
Restructuring reserved settled with cash and other adjustments		(109)		(331)
Restructuring reserve, end		338		291
Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring reserve, beginning		44		124
Restructuring charges		19	[5]	38	[6]
Restructuring reserved settled with cash and other adjustments		(26)		(118)
Restructuring reserve, end		37		44
Wireline [Member]
Restructuring Reserve [Roll Forward]
Severance costs		25		35
Wireline [Member] | Lease [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges				1
Wireline [Member] | Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges				5
Wireline [Member] | cost of products [Member] | Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	[5]	2
Wireless [Member]
Restructuring Reserve [Roll Forward]
Severance costs		191		218
Wireless [Member] | Lease [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges				12
Wireless [Member] | Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges				$ 33
Wireless [Member] | cost of products [Member] | Access [Member]
Restructuring Reserve [Roll Forward]
Restructuring charges	[5]	$ 17

[1] (2)For the Successor year ended March 31, 2016, we recognized costs of $216 million ($191 million Wireless, $25 million Wireline).

[2] (5)For the Successor year ended March 31, 2015, we recognized costs of $253 million ($218 million Wireless, $35 million Wireline).

[3] (1)We recognized costs of $176 million (Wireless only) for the Successor year ended March 31, 2016, which were offset by $20 million of income (Wireless only) resulting from a revision to our estimate of a previously recorded reserve.

[4] (4)We recognized costs of $13 million ($12 million Wireless and $1 million Wireline) for the year ended March 31, 2015, which were offset by $41 million of income (Wireless only) resulting from a revision to our estimate of a previously recorded reserve.

[5] (3)For the Successor year ended March 31, 2016, $2 million (solely attributable to Wireline) was recognized as "Cost of services" and $17 million (solely attributable to Wireless) was recognized as "Severance and exit costs."

[6] (6)For the Successor year ended March 31, 2015, we recognized costs of $38 million ($33 million Wireless, $5 million Wireline).