Derivatives and Hedging Activities (Details Textuals) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Derivative [Line Items]
Derivatives subject to master netting arrangements not offset	$ 0		$ 0		$ 0
Margin on interest rate swaps	61,000,000		61,000,000		47,000,000
Carrying values of hedged liabilities	19,600,000,000		19,600,000,000		22,700,000,000
Cumulative amount of fair value hedging adjustment	810,000,000		810,000,000		217,000,000
Net increase (reduction) in interest expense on long term debt and other	(81,000,000)	$ 36,000,000	(102,000,000)	$ 74,000,000
Gain (loss) on net investment hedges recorded in AOCI, net of taxes	(339,000,000)	87,000,000	393,000,000	(75,000,000)
Gain (loss) on net investment hedges reclassification out of AOCI, net of taxes	1,000,000	0	1,000,000	0
Other Expense [Member]
Derivative [Line Items]
Gain (loss) in changes in fair value of derivatives not designated as hedges	(2,000,000)	23,000,000	18,000,000	27,000,000
Fair Value Hedging [Member] | Fixed-Rate Debt Obligations [Member]
Derivative [Line Items]
Fixed-rate debt obligations designated in fair value hedging relationships	18,800,000,000		18,800,000,000		22,600,000,000
Net Investment Hedges [Member]
Derivative [Line Items]
Notional amounts of derivatives	9,900,000,000		9,900,000,000		$ 9,800,000,000
Accumulated Other Comprehensive Loss [Member]
Derivative [Line Items]
Gain (loss) on net investment hedges recorded in AOCI, net of taxes	$ (339,000,000)	$ 87,000,000	$ 393,000,000	$ (75,000,000)