Property, Plant and Equipment (Components of Property Plant and Equipment) (Details) (Successor [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014
Property, Plant and Equipment [Line Items]
Less accumulated depreciation	$ (3,201)	$ (2,449)
Property, plant and equipment, net	16,852	16,299
Land [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	265	265
Network equipment, site costs and related software [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	15,915	14,902
Building and Building Improvements [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	748	745
Non-network internal use software, office equipment and other [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment	945	866
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Construction in progress	$ 2,180	$ 1,970