Acquisitions (Narrative) (Details) - USD ($) $ in Millions		3 Months Ended	9 Months Ended
	Apr. 01, 2016	Mar. 31, 2017	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Business Acquisition [Line Items]
Cash paid for acquisition	$ 9,871			$ 9,886
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Financial Liabilities			$ 61
Goodwill, Purchase Accounting Adjustments			98
Goodwill			9,102		$ 9,674
Capital Expenditures Integration Activities			19	99
CTF Transaction [Member]
Business Acquisition [Line Items]
Acquisition purchase price			10,540
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		$ 20
Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Property, Plant, and Equipment			(140)
Goodwill			2,606
Capital Expenditures Integration Activities			$ 19	$ 99