Property, Plant and Equipment Property, Plant and Equipment (Narrative) (Details) (USD $) In Millions, unless otherwise specified	6 Months Ended
Sep. 30, 2013 Predecessor [Member]	Sep. 30, 2014 Successor [Member]	Sep. 30, 2014 Leased handset [Member] Successor [Member]
Property, Plant and Equipment [Line Items]
Property, Plant and Equipment, Additions	$ 50	$ 570	$ 70

Amount of acquisition of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include, but are not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

No definition available.

Name:	us-gaap_PropertyPlantAndEquipmentAdditions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration