Hedging Activities (Narrative) (Details) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Derivative Asset, Notional Amount	$ 17,285	$ 18,609
Gross Notional Value, Translated Earnings Contracts [Member]
Derivative Asset, Notional Amount	15,400	16,700
Gross Notional Value, Collar Options [Member]
Derivative Asset, Notional Amount	1,600	2,000
Gross Notional Value, Foreign Exchange Forward [Member]
Derivative Asset, Notional Amount	13,900	14,700
Gross Notional Value, Foreign Exchange Forward [Member] | Not Designated as Hedging Instrument [Member]
Derivative Asset, Notional Amount	12,800	13,600
Net Notional Value, Collar Options [Member]
Derivative Asset, Notional Amount	$ 800	$ 1,000