v2.4.1.9
Valuation and Qualifying Accounts (Detail) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Allowance for Doubtful Accounts      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance at Beginning of Period $ 645us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 $ 641us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 $ 802us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember
Charged to expenses 1,095us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 993us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 972us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember
Charged to other Accounts 141us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 [1],[2] 162us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 [1],[2] 113us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 [1],[2]
Deductions 1,142us-gaap_ValuationAllowancesAndReservesDeductions
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 [3],[4] 1,151us-gaap_ValuationAllowancesAndReservesDeductions
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 [3],[4] 1,246us-gaap_ValuationAllowancesAndReservesDeductions
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 [3],[4]
Balance at End of Period 739us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 645us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember		 641us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_AllowanceForDoubtfulAccountsMember
Valuation Allowance of Deferred Tax Assets      
Valuation and Qualifying Accounts Disclosure [Line Items]      
Balance at Beginning of Period 1,685us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5] 2,096us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5] 2,410us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5]
Charged to expenses 505us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5] 235us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5] 120us-gaap_ValuationAllowancesAndReservesChargedToCostAndExpense
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5]
Charged to other Accounts 5us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [1],[2],[5] 64us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [1],[2],[5] 82us-gaap_ValuationAllowancesAndReservesChargedToOtherAccounts
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [1],[2],[5]
Deductions 354us-gaap_ValuationAllowancesAndReservesDeductions
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [3],[4],[5] 710us-gaap_ValuationAllowancesAndReservesDeductions
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [3],[4],[5] 516us-gaap_ValuationAllowancesAndReservesDeductions
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [3],[4],[5]
Balance at End of Period $ 1,841us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5] $ 1,685us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5] $ 2,096us-gaap_ValuationAllowancesAndReservesBalance
/ us-gaap_ValuationAllowancesAndReservesTypeAxis
= us-gaap_ValuationAllowanceOfDeferredTaxAssetsMember		 [5]
[1] Allowance for Uncollectible Accounts Receivable primarily includes amounts previously written off which were credited directly to this account when recovered.
[2] Valuation Allowance for Deferred Tax Assets includes current year increase to valuation allowance charged to equity and reclassifications from other balance sheet accounts.
[3] Amounts written off as uncollectible or transferred to other accounts or utilized.
[4] Reductions to valuation allowances related to deferred tax assets.
[5] The presentation of the Valuation Allowance for Deferred Tax Assets has been updated to reflect the impact of the Wireless Transaction.