Derivatives and Hedging Activities (Details Textuals) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Derivative [Line Items]
Margin on interest rate swaps	$ 15,000,000		$ 15,000,000		$ 34,000,000
Carrying values of hedged liabilities	13,200,000,000		13,200,000,000		16,400,000,000
Cumulative amount of fair value hedging adjustment	365,000,000		365,000,000		622,000,000
Net decrease in interest expense on long term debt and other	60,000,000	$ 81,000,000	196,000,000	$ 183,000,000
Not Designated as Hedging Instrument
Derivative [Line Items]
Notional amount of derivatives	16,800,000,000		16,800,000,000		14,400,000,000
Other Expense
Derivative [Line Items]
(Loss) gain in changes in fair value of derivatives not designated as hedges	(10,000,000)	4,000,000	(24,000,000)	22,000,000
Fair Value Hedging | Fixed-Rate Debt Obligations
Derivative [Line Items]
Fixed-rate debt obligations designated in fair value hedging relationships	12,900,000,000		12,900,000,000		15,800,000,000
Net Investment Hedges
Derivative [Line Items]
Notional amount of derivatives	11,400,000,000		11,400,000,000		$ 10,500,000,000
Gain (loss) on net investment hedges, net of taxes	155,000,000	(170,000,000)	53,000,000	223,000,000
Reclassifications out of AOCI	$ 0	$ 0	$ 0	$ 0