Basis of Presentation Basis of Presentation (Details 2) $ in Millions		3 Months Ended			9 Months Ended
	Aug. 27, 2015 USD ($)	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)	Sep. 30, 2015 USD ($)	Sep. 30, 2014 USD ($)
Operating revenues by products and services
Revenues			$ 4,554	$ 4,514	$ 13,424	$ 13,593
CAF Phase 2 Support
Operating revenues by products and services
Federal support, total amount per agreement	$ 500
Number of states in which service is provided (states)			33		33
Revenues			$ 158
Contract or agreement term	6
Number of rural households and businesses	1,200,000
CAF Phase 2 Support | Forecast
Operating revenues by products and services
Revenues		$ 50