Other Financial Information (Details) - USD ($) $ in Millions	6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Other Current Assets
Prepaid expenses	$ 286		$ 260
Materials, supplies and inventory	124		132
Assets held for sale	10		14
Deferred activation and installation charges	105		103
Other	74		71
Total other current assets	599		580
Impairment of long-lived assets	8	$ 32
Selected Current Liabilities
Accounts payable	1,049		1,226
Other Current Liabilities
Accrued rent	31		34
Legal contingencies	24		27
Other	170		149
Total other current liabilities	225		210
Current Liabilities
Book overdraft balance	65		80
Capital expenditures incurred but not yet paid	120		$ 185
Building
Other Current Assets
Impairment of long-lived assets	$ 8