Financial Instruments (Foreign Exchange Risk) (Details) - USD ($) $ in Billions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Foreign Exchange Forward
Derivative [Line Items]
Aggregate notional amount	$ 1.2	$ 1.4
Foreign Exchange Contract
Derivative [Line Items]
Maturity period	60 days
Maximum | Foreign Exchange Contract
Derivative [Line Items]
Maturity period	180 days