Derivatives and Hedging Activities Textuals (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Derivatives And Hedging Activities Textuals [Abstract]
Net (increase) reduction in interest expense on long term debt.	$ (23)	$ 8	$ (46)	$ 47
Derivative [Line Items]
Notional amount of long-term debt	14,200		14,200		$ 16,000
Loss (gain) on net investment hedges	3	95	(59)	263
Amounts reclassified from AOCI into income	0	0	0	0
Margin on interest rate swap not netted	67		67		115
Gain in Changes of Fair Value of Derivatives not designated as hedges	10	$ 8	40	$ 19
Cumulative fair value hedging adjustment of hedged item in fair value hedge	(278)		(278)		(155)
Fair Value Hedging [Member]
Derivative [Line Items]
Notional amount of long-term debt	$ 14,500		$ 14,500		$ 16,200