Securities - Additional Information (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) Investment		Mar. 31, 2021 USD ($)	Dec. 31, 2021 USD ($) Investment
Schedule of Investments [Line Items]
Federal Home Loan Bank stock, at cost | $	$ 679	[1]		$ 734	[2]
Net losses on equity securities | $	$ 1		$ 0
Collateralized Mortgage Obligations
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more	11			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			4
Corporate Bonds
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more	2			2
U.S. Government Agency Bonds
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more	24			20
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
Mortgage-Related Securities
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more	31
Agency Mortgage-backed Securities
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more				21
Equity Securities
Schedule of Investments [Line Items]
Number of investment securities designated as having a continuous loss position for twelve months or more	1

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

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