Acquisitions (Narrative) (Details) item in Millions, customer in Millions, $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($) customer item	Mar. 31, 2016 USD ($)	Dec. 31, 2016 USD ($)
Business Acquisition [Line Items]
Goodwill	$ 9,772		$ 9,674
Capital Expenditures Integration Activities	1	$ 52
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities	61
Goodwill, Purchase Accounting Adjustments	98
CTF Transaction [Member]
Business Acquisition [Line Items]
Acquisition purchase price	10,540
Cash paid for acquisition	9,871
Working Capital and Net Debt Settlement Payments Received	15
Goodwill	$ 2,606
Number of voice connections acquired | customer	2.5
Number of broadband connections acquired | item	2.1
Number of video connections acquired | item	1.2
Revenue	$ 1,087
Operating income	100
Capital Expenditures Integration Activities	1	$ 52
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment	140
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment	6,096
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Intangibles	100
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Finite-Lived Intangibles	2,262		$ 2,162
Business Combination Provisional Information Initial Accounting Incomplete Adjustments Related to Previous Period Amortization	$ 20