Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2022		Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 5,612		$ 5,780
Total equity securities	15		16
Total securities	5,627	[1]	5,796	[2]
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	5,612		5,780
Total equity securities	15		16
Total securities	5,627		5,796
Fair Value, Measurements, Recurring | Mutual Funds and Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	15		16
Fair Value, Measurements, Recurring | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,616		2,790
Fair Value, Measurements, Recurring | Mortgage-Related Securities | GSE Certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,063		1,107
Fair Value, Measurements, Recurring | Mortgage-Related Securities | GSE CMOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,553		1,683
Fair Value, Measurements, Recurring | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,996		2,990
Fair Value, Measurements, Recurring | Other Securities | U.S. Treasury Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	144		45
Fair Value, Measurements, Recurring | Other Securities | GSE Debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,373		1,480
Fair Value, Measurements, Recurring | Other Securities | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	456		479
Fair Value, Measurements, Recurring | Other Securities | Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	24		25
Fair Value, Measurements, Recurring | Other Securities | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	878		838
Fair Value, Measurements, Recurring | Other Securities | Foreign Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	26		26
Fair Value, Measurements, Recurring | Other Securities | Capital Trust Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	95		97
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	144		45
Total securities	144		45
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale			2,790
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-Related Securities | GSE Certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale			1,107
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-Related Securities | GSE CMOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale			1,683
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	144		45
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Securities | U.S. Treasury Obligations
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	144		45
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	5,468		5,735
Total equity securities	15		16
Total securities	5,483		5,751
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mutual Fund
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities			16
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mutual Funds and Common Stock
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total equity securities	15
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,616
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-Related Securities | GSE Certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,063
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-Related Securities | GSE CMOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,553
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,852		2,945
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | GSE Certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale			1,480
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | GSE Debentures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,373
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | Asset-backed Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	456		479
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	24		25
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	878		838
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | Foreign Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	26		26
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Securities | Capital Trust Notes
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 95		$ 97

[1] Excludes accrued interest receivable of $15 million included in other assets in the Consolidated Statements of Condition.

[2] Excludes accrued interest receivable of $15 million included in other assets in the Consolidated Statements of Condition.