Equipment Installment Plan Receivables (EIP Receivables) (Details) (Equipment Installment Plan Receivable [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Equipment Installment Plan Receivables [Line Items]
Equipment installment plan, maximum payment terms	24 months
Equipment installment plan receivables, gross	$ 4,403	$ 2,882
Equipment installment plan receivables, deferred interest and allowance for credit losses	(440)	(336)
Equipment installment plan receivables, net of deferred interest	4,094	2,606
Equipment installment plan receivables, net	3,963	2,546
Deferred Interest [Member]
Equipment Installment Plan Receivables [Line Items]
Equipment installment plan receivables, deferred interest and allowance for credit losses	(309)	(276)
Allowances for Credit Losses [Member]
Equipment Installment Plan Receivables [Line Items]
Equipment installment plan receivables, deferred interest and allowance for credit losses	(131)	(60)
Accounts Receivable, Net [Member]
Equipment Installment Plan Receivables [Line Items]
Equipment installment plan receivables, net	2,553	1,471
Other Assets [Member]
Equipment Installment Plan Receivables [Line Items]
Equipment installment plan receivables, net	$ 1,410	$ 1,075