Derivatives and Hedging Activities (Details 1) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Other Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fixed-rate long-term debt		$ 39		$ 64
Derivatives designated as hedging instruments		(31)		(100)
Total		$ 8		$ (36)
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fixed-rate long-term debt	$ 63		$ 331
Derivatives designated as hedging instruments	(65)		(323)
Total	$ (2)		$ 8