Commitments and Contingencies (Narrative) (Details) (USD $)	0 Months Ended	12 Months Ended	3 Months Ended	6 Months Ended	12 Months Ended	3 Months Ended	12 Months Ended
	Apr. 19, 2012	Mar. 31, 2015 renewal_option	Mar. 31, 2014	Jul. 10, 2013	Dec. 31, 2012	Jun. 30, 2014	Dec. 31, 2013
Commitments and Contingencies [Line Items]
Sales receipts alleged to not be reported, amount	$ 100,000,000
Minimum spectrum reconfiguration obligations		2,800,000,000
Total Payments directly attributable to performance under Report and Order		3,400,000,000
Noncancelable portion of leases, maximum		15 years
Number of operating lease renewals available		1
Operating lease, maximum contract length to become eligible for renewal contract, term		10 years
General initial term of operating lease, minimum		5 years
General initial term of operating lease, maximum		12 years
Number of cell site renewal options available		5.0
Years for each renewal option for cell site leases		5 years
Maximum length of spectrum lease agreements		30 years
Maximum remaining commitments of other spectrum commitments		90,000,000
Predecessor [Member]
Commitments and Contingencies [Line Items]
Operating leases, rent expense, net			483,000,000	1,000,000,000	2,000,000,000
Successor [Member]
Commitments and Contingencies [Line Items]
Payments directly attributable to performance under report and order, net change		157,000,000
Licensees reimbursed share of costs						95,000,000
Operating leases, rent expense, net		2,600,000,000	653,000,000				1,300,000,000
Payment to satisfy other spectrum commitments		9,000,000
Minimum [Member]
Commitments and Contingencies [Line Items]
Remaining other spectrum commitments expected to be incurred over term		15 years
Maximum [Member]
Commitments and Contingencies [Line Items]
Remaining other spectrum commitments expected to be incurred over term		30 years
Letter Of Credit Required By The FCCs Report And Order [Member] | Unsecured Revolving Credit Facility expires in 2018 [Member]
Commitments and Contingencies [Line Items]
Initial letter of credit requirement		2,500,000,000
Letters of credit outstanding, amount		$ 406,000,000