Derivatives and Hedging Activities (Details 1) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Other Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fixed-rate long-term debt		$ (25)		$ 25
Derivatives designated as hedging instruments		6		(69)
Total		$ (19)		$ (44)
Interest Expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Fixed-rate long-term debt	$ 58		$ 268
Derivatives designated as hedging instruments	(67)		(258)
Total	$ (9)		$ 10