Securities - Additional Information (Details) $ in Millions		12 Months Ended
		Dec. 31, 2021 USD ($) Investment	Dec. 31, 2020 USD ($) Investment	Dec. 31, 2019 USD ($)
Schedule of Investments [Line Items]
Federal Home Loan Bank stock, at cost | $	[1]	$ 734	$ 714
Net gains on equity securities | $		$ 0	$ 1	$ 2
Collateralized Mortgage Obligations
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		4	4
Capital Trust Notes
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		5	5
Asset-backed Securities
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		4	7
Corporate Bonds
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		2	3
Municipal Bonds
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		1	1
US Government Agencies Securities
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		20
Mortgage-Related Securities
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more		21

[1] Carrying value and estimated fair value are at cost.