Investment Securities (Narrative) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Schedule of Investments [Line Items]
Net unsettled investment purchases	$ 800	$ 200
Investment securities, allowance for credit loss	133	82
Provision for credit losses on investment securities	51	$ 80
Federal National Mortgage Association Certificates and Obligations (FNMA)
Schedule of Investments [Line Items]
Amortized cost of debt securities of a single issuer that exceeds 10 percent of shareholders equity	33,800
Fair value of debt securities of a single issuer that exceeds 10 percent of shareholders equity	34,200
Federal Home Loan Mortgage Corp (FHLMC)
Schedule of Investments [Line Items]
Amortized cost of debt securities of a single issuer that exceeds 10 percent of shareholders equity	25,000
Fair value of debt securities of a single issuer that exceeds 10 percent of shareholders equity	$ 24,800