Commitments, Contingencies and Other Items - Other Commitments (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 year	Dec. 31, 2013	Dec. 31, 2012
Commitments and Contingencies Disclosure [Abstract]
Amount outstanding under letters of credit	$ 28	$ 29
Collateralized Financings	23	25
Payments under these right-of-way agreements	173	161	172
Rent expense, including common area maintenance, under non-cancelable lease agreements	318	311	308
Right-of-Way Agreements
Right-of-Way Agreements, 2013	118
Right-of-Way Agreements, 2014	58
Right-of-Way Agreements, 2015	53
Right-of-Way Agreements, 2016	51
Right-of-Way Agreements, 2017	42
Right-of-Way Agreements, Thereafter	315
Right-of-Way Agreements, Total	637
Facilities
Facilities, 2013	302
Facilities, 2014	244
Facilities, 2015	207
Facilities, 2016	174
Facilities, 2017	142
Facilities, Thereafter	655
Facilities, Total	1,724
Total
Right-of-Way Agreements and Facilities, 2013	420
Right-of-Way Agreements and Facilities, 2014	302
Right-of-Way Agreements and Facilities, 2015	260
Right-of-Way Agreements and Facilities, 2016	225
Right-of-Way Agreements and Facilities, 2017	184
Right-of-Way Agreements and Facilities, Thereafter	970
Right-of-Way Agreements and Facilities, Total	2,361
Future Minimum Sublease Receipts
2013	5
2014	4
2015	4
2016	1
2017	1
Thereafter	0
Total	$ 15
Period of Right-of-Way Agreements with cancelable agreements (in years)	1