Acquisitions (Narrative) (Details) item in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015 USD ($) item	Sep. 30, 2015 USD ($)	Jun. 30, 2015 USD ($)	Mar. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Sep. 30, 2014 USD ($)	Jun. 30, 2014 USD ($)	Mar. 31, 2014 USD ($)	Dec. 31, 2015 USD ($) item	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Business Acquisition [Line Items]
Cash paid for acquisition									$ 17,000,000	$ 2,018,000,000
Acquisition and integration costs	$ 86,000,000	$ 58,000,000	$ 35,000,000	$ 57,000,000	$ 70,000,000	$ 42,000,000	$ 19,000,000	$ 11,000,000	236,000,000	142,000,000	$ 10,000,000
Capital Expenditures Integration Activities									153,000,000	116,000,000
Revenue	1,413,000,000	1,424,000,000	1,368,000,000	1,371,000,000	1,330,000,000	1,141,000,000	1,147,000,000	1,154,000,000	5,576,000,000	4,772,000,000	4,762,000,000
Operating income	182,000,000	207,000,000	193,000,000	$ 163,000,000	173,000,000	$ 197,000,000	$ 224,000,000	$ 226,000,000	745,000,000	820,000,000	981,000,000
Goodwill	7,166,000,000				$ 7,205,000,000				7,166,000,000	7,205,000,000
Restricted cash, excluding interest income	8,440,000,000								8,440,000,000
Restricted cash	8,444,000,000								8,444,000,000
Interest Income [Member]
Business Acquisition [Line Items]
Restricted cash	4,000,000								4,000,000
2015 JP Morgan Credit Agreement [Member]
Business Acquisition [Line Items]
Debt instrument, face amount	1,500,000,000								1,500,000,000
Connecticut Operations [Member]
Business Acquisition [Line Items]
Acquisition and integration costs									40,000,000	142,000,000
Acquisition costs									1,000,000	15,000,000	$ 10,000,000
Integration costs									39,000,000	127,000,000
Capital Expenditures Integration Activities									24,000,000	116,000,000
Revenue									1,049,000,000	216,000,000
Operating income									100,000,000	$ 38,000,000
Goodwill	815,000,000								815,000,000
Goodwill deductible for income tax purposes	75,000,000								75,000,000
Verizon Transaction [Member]
Business Acquisition [Line Items]
Acquisition purchase price	$ 10,540,000,000								10,540,000,000
Acquisition and integration costs									196,000,000
Acquisition costs									44,000,000
Integration costs									152,000,000
Capital Expenditures Integration Activities									$ 129,000,000
Number of voice connections acquired | item	3.3								3.3
Number of broadband connections acquired | item	2.1								2.1
Number of video connections acquired | item	1.2								1.2
Connect America Funding Conditionally Accepted									$ 49,000,000
Proceeds from equity issuance			$ 2,750,000,000
Verizon Transaction [Member] | Senior Unsecured Debt [Member]
Business Acquisition [Line Items]
Debt instrument, face amount		6,600,000,000
Verizon Transaction [Member] | 2015 JP Morgan Credit Agreement [Member]
Business Acquisition [Line Items]
Debt instrument, face amount		$ 1,500,000,000