Derivatives and Hedging Activities (Details Textuals) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Derivative [Line Items]
Carrying values of hedged liabilities	$ 16,500,000,000		$ 16,500,000,000		$ 22,700,000,000
Cumulative amount of fair value hedging adjustment	714,000,000		714,000,000		217,000,000
Net increase (reduction) in interest expense on long term debt and other	(81,000,000)	$ 28,000,000	(183,000,000)	$ 102,000,000
Gain (loss) on net investment hedges recorded in AOCI, net of taxes	(170,000,000)	138,000,000	223,000,000	63,000,000
Gain (loss) on net investment hedges reclassification out of AOCI, net of taxes	0	0	1,000,000	0
Other Expense [Member]
Derivative [Line Items]
Gain (loss) in changes in fair value of derivatives not designated as hedges	4,000,000	25,000,000	22,000,000	52,000,000
Fair Value Hedging [Member] | Fixed-Rate Debt Obligations [Member]
Derivative [Line Items]
Fixed-rate debt obligations designated in fair value hedging relationships	15,800,000,000		15,800,000,000		22,600,000,000
Net Investment Hedges [Member]
Derivative [Line Items]
Notional amounts of derivatives	10,100,000,000		10,100,000,000		$ 9,800,000,000
Accumulated Other Comprehensive Loss [Member]
Derivative [Line Items]
Gain (loss) on net investment hedges recorded in AOCI, net of taxes	$ (170,000,000)	$ 138,000,000	$ 223,000,000	$ (63,000,000)