Segment Information Revenue From External Customers (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Segment information
Revenue from external customers	$ 1,914	$ 1,629	$ 1,625	$ 1,609	$ 1,602	$ 1,569	$ 1,565	$ 1,577	$ 6,777	$ 6,313	$ 6,376
Core Network Service [Member]
Segment information
Revenue from external customers									6,195	5,591	5,463
Core Network Service [Member] | North America
Segment information
Revenue from external customers									4,240	3,949	3,840
Core Network Service [Member] | Europe
Segment information
Revenue from external customers									891	888	911
Core Network Service [Member] | Latin America
Segment information
Revenue from external customers									779	754	712
tw telecom [Member] | Latin America
Segment information
Revenue from external customers									285	0
Wholesale Voice Services and Other [Member]
Segment information
Revenue from external customers									582	722	913
Wholesale Voice Services and Other [Member] | North America
Segment information
Revenue from external customers									530	681	863
Wholesale Voice Services and Other [Member] | Europe
Segment information
Revenue from external customers									19	31	40
Wholesale Voice Services and Other [Member] | Latin America
Segment information
Revenue from external customers									$ 33	$ 10	$ 10