Derivatives and Hedging Activities (Details Textuals) - USD ($)	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Derivative [Line Items]
Margin on interest rate swaps	$ 28,000,000		$ 34,000,000
Carrying values of hedged liabilities	16,200,000,000		16,400,000,000
Cumulative amount of fair value hedging adjustment	479,000,000		622,000,000
Net decrease in interest expense on long term debt and other	73,000,000	$ 21,000,000
Other Expense
Derivative [Line Items]
(Gain) loss on changes in fair value of derivatives and related underlying foreign currency exposures	5,000,000	(20,000,000)
Fair Value Hedging | Fixed-Rate Debt Obligations
Derivative [Line Items]
Fixed-rate debt obligations designated in fair value hedging relationships	15,800,000,000		15,800,000,000
Net Investment Hedges
Derivative [Line Items]
Notional amounts of derivatives	10,500,000,000		$ 10,500,000,000
Gain on net investment hedges recorded in AOCI, net of taxes	6,000,000	732,000,000
Reclassifications out of AOCI	$ 0	$ 0