Severance and Exit Costs (Details) - USD ($) $ in Millions		3 Months Ended		9 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Restructuring Cost and Reserve [Line Items]
Severance Costs	[1]	$ 176		$ 194
Restructuring Charges				227
Lease and access exit costs [Member] | Minimum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring And Related Cost Expected Future Cost				100
Lease and access exit costs [Member] | Maximum [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring And Related Cost Expected Future Cost				175
Wireless [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs		$ 156
Other Operating Income (Expense) [Member] | Wireless [Member]
Restructuring Cost and Reserve [Line Items]
Severance Costs	[1]			172
Restructuring Reserve, Accrual Adjustment			$ 41	$ 20	$ 41

[1] For the three and nine-month periods ended December 31, 2015, we recognized costs of $176 million ($156 million Wireless, $20 million Wireline), and $194 million ($172 million Wireless, $22 million Wireline), respectively, included in "Severance and Exit Costs" on the consolidated statements of comprehensive loss.