Financial Derivatives (Narrative) (Details) - USD ($)	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative [Line Items]
Cash and securities held to collateralize net derivative assets	$ 1,500,000,000
Cash and securities pledged to collateralize net derivative liabilities	4,400,000,000
Cash flow hedges | Interest Rate Contracts
Derivative [Line Items]
Cash flow hedge gain (loss) to be reclassified within twelve months	300,000,000
Cash flow hedge gain (loss) to be reclassified within twelve months, net of tax	$ 231,000,000
Maximum length of time hedged in cash flow hedge	10 years
Net investment hedges | Foreign exchange contracts:
Derivative [Line Items]
Gain loss from components excluded from assessment of net investment hedge effectiveness net	$ 0	$ 0