Guarantor Financial Information CONDENSED CONSOLIDATING BALANCE SHEET (Details) (Successor [Member], USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2013	Mar. 31, 2013
Current Assets
Cash and cash equivalents, beginning of period	$ 4,171	$ 4,970	$ 11	$ 3
Short-term Investments	1,322	1,220
Accounts and notes receivable, net	3,751	3,607
Device and accessory inventory	1,116	982
Current deferred tax asset	78	128
Prepaid expenses and other current assets	936	672
Total current assets	11,374	11,579
Equity Method Investments And Other	143	146
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Property, plant and equipment, net	16,852	16,299
Due from Affiliate, Noncurrent	0	0
Note receivable from consolidated affiliate	0	0
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	6,343	6,383
FCC licenses and other	41,764	41,978
Definite-lived intangible assets, net	7,119	7,558
Other assets	824	746
Total assets	84,419	84,689
Current Liabilities
Accounts Payable, Current	3,492	3,163
Accrued expenses and other current liabilities	5,137	5,544
Current portion of long-term debt, financing and capital lease obligations	807	991
Total current liabilities	9,436	9,698
Long-term debt, financing and capital lease obligations	31,687	31,787
Deferred Tax Liabilities, Net, Noncurrent	14,268	14,207
Note due to consolidated affiliate	0	0
Other liabilities	3,664	3,685
Due to Affiliate, Noncurrent	0	0
Total liabilities	59,055	59,377
Commitments and contingencies
Total shareholders' equity	25,364	25,312
Liabilities and Equity	84,419	84,689
Parent Company [Member]
Current Assets
Cash and cash equivalents, beginning of period	0	0
Short-term Investments	0	0
Accounts and notes receivable, net	152	74
Device and accessory inventory	0	0
Current deferred tax asset	0	0
Prepaid expenses and other current assets	0	0
Total current assets	152	74
Equity Method Investments And Other	0	0
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	25,368	25,316
Property, plant and equipment, net	0	0
Due from Affiliate, Noncurrent	0	0
Note receivable from consolidated affiliate	9,000	9,000
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	0	0
FCC licenses and other	0	0
Definite-lived intangible assets, net	0	0
Other assets	130	133
Total assets	34,650	34,523
Current Liabilities
Accounts Payable, Current	0	0
Accrued expenses and other current liabilities	156	78
Current portion of long-term debt, financing and capital lease obligations	0	0
Total current liabilities	156	78
Long-term debt, financing and capital lease obligations	9,000	9,000
Deferred Tax Liabilities, Net, Noncurrent	0	0
Note due to consolidated affiliate	0	0
Other liabilities	0	0
Due to Affiliate, Noncurrent	130	133
Total liabilities	9,286	9,211
Total shareholders' equity	25,364	25,312
Liabilities and Equity	34,650	34,523
Guarantor Subsidiaries [Member]
Current Assets
Cash and cash equivalents, beginning of period	3,545	4,125
Short-term Investments	1,322	1,220
Accounts and notes receivable, net	48	27
Device and accessory inventory	0	0
Current deferred tax asset	0	0
Prepaid expenses and other current assets	19	14
Total current assets	4,934	5,386
Equity Method Investments And Other	1,112	1,104
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	25,956	25,588
Property, plant and equipment, net	0	0
Due from Affiliate, Noncurrent	18,299	18,234
Note receivable from consolidated affiliate	0	0
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	0	0
FCC licenses and other	0	0
Definite-lived intangible assets, net	0	0
Other assets	130	133
Total assets	50,431	50,445
Current Liabilities
Accounts Payable, Current	0	0
Accrued expenses and other current liabilities	498	493
Current portion of long-term debt, financing and capital lease obligations	0	0
Total current liabilities	498	493
Long-term debt, financing and capital lease obligations	14,966	15,027
Deferred Tax Liabilities, Net, Noncurrent	0	0
Note due to consolidated affiliate	9,000	9,000
Other liabilities	599	609
Due to Affiliate, Noncurrent	0	0
Total liabilities	25,063	25,129
Total shareholders' equity	25,368	25,316
Liabilities and Equity	50,431	50,445
Non-Guarantor Subsidiaries [Member]
Current Assets
Cash and cash equivalents, beginning of period	626	845
Short-term Investments	0	0
Accounts and notes receivable, net	3,751	3,607
Device and accessory inventory	1,116	982
Current deferred tax asset	78	128
Prepaid expenses and other current assets	917	658
Total current assets	6,488	6,220
Equity Method Investments And Other	50	61
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	0	0
Property, plant and equipment, net	16,852	16,299
Due from Affiliate, Noncurrent	0	0
Note receivable from consolidated affiliate	0	0
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	6,343	6,383
FCC licenses and other	41,764	41,978
Definite-lived intangible assets, net	7,119	7,558
Other assets	694	613
Total assets	79,310	79,112
Current Liabilities
Accounts Payable, Current	3,492	3,163
Accrued expenses and other current liabilities	4,683	5,074
Current portion of long-term debt, financing and capital lease obligations	807	991
Total current liabilities	8,982	9,228
Long-term debt, financing and capital lease obligations	8,740	8,779
Deferred Tax Liabilities, Net, Noncurrent	14,268	14,207
Note due to consolidated affiliate	0	0
Other liabilities	3,065	3,076
Due to Affiliate, Noncurrent	18,299	18,234
Total liabilities	53,354	53,524
Total shareholders' equity	25,956	25,588
Liabilities and Equity	79,310	79,112
Consolidation, Eliminations [Member]
Current Assets
Cash and cash equivalents, beginning of period	0	0
Short-term Investments	0	0
Accounts and notes receivable, net	(200)	(101)
Device and accessory inventory	0	0
Current deferred tax asset	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(200)	(101)
Equity Method Investments And Other	(1,019)	(1,019)
Investments in and Advance to Affiliates, Subsidiaries, Associates, and Joint Ventures	(51,324)	(50,904)
Property, plant and equipment, net	0	0
Due from Affiliate, Noncurrent	(18,299)	(18,234)
Note receivable from consolidated affiliate	(9,000)	(9,000)
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill	0	0
FCC licenses and other	0	0
Definite-lived intangible assets, net	0	0
Other assets	(130)	(133)
Total assets	(79,972)	(79,391)
Current Liabilities
Accounts Payable, Current	0	0
Accrued expenses and other current liabilities	(200)	(101)
Current portion of long-term debt, financing and capital lease obligations	0	0
Total current liabilities	(200)	(101)
Long-term debt, financing and capital lease obligations	(1,019)	(1,019)
Deferred Tax Liabilities, Net, Noncurrent	0	0
Note due to consolidated affiliate	(9,000)	(9,000)
Other liabilities	0	0
Due to Affiliate, Noncurrent	(18,429)	(18,367)
Total liabilities	(28,648)	(28,487)
Total shareholders' equity	(51,324)	(50,904)
Liabilities and Equity	$ (79,972)	$ (79,391)