Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2022		Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	$ 6,689		$ 5,780
Total equity securities	14		16
Total securities	6,703	[1]	5,796	[2]
Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	2,230		2,790
Mortgage-Related Securities | GSE Certificates
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	944		1,107
Mortgage-Related Securities | GSE CMOs
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	1,286		1,683
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Securities available for sale	6,689		5,780
Total equity securities	14		16
Total securities	6,703		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	14		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	2,230		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	944		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	1,286		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	4,459		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	1,672		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	1,406		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	391		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	18		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	855		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	25		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	92		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	1,672		45
Total securities	1,672		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	1,672		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	1,672		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	5,017		5,735
Total equity securities	14		16
Total securities	5,031		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	14
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	2,230
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	944
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	1,286
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	2,787		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	1,406
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	391		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	18		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	855		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	25		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	$ 92		$ 97

[1] Excludes accrued interest receivable of $23 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.