Equipment Installment Plan Receivables (Deferred Interest and Allowance for Credit Losses) (Details) (Equipment Installment Plan Receivable [Member], USD $) In Millions, unless otherwise specified	9 Months Ended
	Sep. 30, 2014	Sep. 30, 2014 Deferred Interest, Long-term [Member]	Dec. 31, 2013 Deferred Interest, Long-term [Member]
Equipment Installment Plan Receivables, Deferred Interest and Allowance for Credit Losses [Roll Forward]
Deferred interest and allowance for credit losses, beginning of period	$ 336	$ 56	$ 64
Bad debt expense	217
Write-offs, net of recoveries	(146)
Change in deferred interest on short-term and long-term EIP receivables	33
Deferred interest and allowance for credit losses, end of period	$ 440	$ 56	$ 64