Other Financial Information (Details) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2016	Dec. 31, 2015
Prepaid Expenses and Other Current Assets [Abstract]
Prepaid expenses	$ 271	$ 238
Materials, supplies and inventory	136	144
Assets held for sale	1	8
Deferred activation and installation charges	111	105
Other	112	86
Total other current assets	631	581
Accounts Payable, Current [Abstract]
Accounts payable	1,036	968
Book overdraft balance	59	68
Capital expenditures incurred but not yet paid	110	94
Other Current Liabilities
Accrued rent	29	32
Legal contingencies	46	20
Other	180	168
Total other current liabilities	$ 255	$ 220

Carrying value as of the balance sheet date of liabilities incurred (and for which invoices have typically been received) and payable to vendors for goods and services received that are used in an entity's business. Used to reflect the current portion of the liabilities (due within one year or within the normal operating cycle if longer).

Name:	us-gaap_AccountsPayableCurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.