Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Dec. 31, 2022		Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	$ 9,060		$ 5,780
Total equity securities	14		16
Total securities	9,074	[1]	5,796	[2]
Total assets at fair value	69		64
Total liabilities at fair value	1,115
Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	4,789		2,790
GSE Certificates | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,297		1,107
GSE CMOs | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	3,301		1,683
Fair Value, Measurements, Recurring
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	9,060		5,780
Total equity securities	14		16
Total securities	9,074		5,796
Mortgage servicing rights	1,033
Total assets at fair value	11,451
Total liabilities at fair value	136
Fair Value, Measurements, Recurring | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	4,789		2,790
Fair Value, Measurements, Recurring | Residential First Mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	1,115
Fair Value, Measurements, Recurring | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	4,271		2,990
Fair Value, Measurements, Recurring | GSE Certificates | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,297		1,107
Fair Value, Measurements, Recurring | GSE CMOs | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	3,301		1,683
Fair Value, Measurements, Recurring | Private Label CMOs | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	191
Fair Value, Measurements, Recurring | U.S. Treasury Obligations | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,487		45
Fair Value, Measurements, Recurring | GSE Debentures | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,398		1,480
Fair Value, Measurements, Recurring | Asset-backed Securities | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	361		479
Fair Value, Measurements, Recurring | Municipal Bonds | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	30		25
Fair Value, Measurements, Recurring | Corporate Bonds | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	885		838
Fair Value, Measurements, Recurring | Foreign Notes | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	20		26
Fair Value, Measurements, Recurring | Capital Trust Notes | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	90		97
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-backed securities forwards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 36
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Derivative liabilities	$ 61
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities
Fair Value, Measurements, Recurring | Interest rate swaps and swaptions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 182
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Derivative liabilities	$ 65
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities
Fair Value, Measurements, Recurring | Futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 2
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Fair Value, Measurements, Recurring | Rate lock commitments (fallout-adjusted)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 9
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Derivative liabilities	$ 10
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities
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]
Investment securities available-for-sale	$ 1,487		45
Total securities	1,487		45
Total assets at fair value	1,487
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]
Investment securities available-for-sale	1,487		45
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U.S. Treasury Obligations | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,487		45
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	7,573		5,735
Total equity securities	14		16
Total securities	7,587		5,751
Total assets at fair value	8,922
Total liabilities at fair value	126
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]
Investment securities available-for-sale	4,789		2,790
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Residential First Mortgage
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Loans held-for-sale	1,115
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]
Investment securities available-for-sale	2,784		2,945
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | GSE Certificates | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,297		1,107
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | GSE CMOs | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	3,301		1,683
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Private Label CMOs | Mortgage-Related Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	191
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | GSE Debentures | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	1,398		1,480
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed Securities | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	361		479
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Municipal Bonds | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	30		25
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate Bonds | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	885		838
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Foreign Notes | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	20		26
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Capital Trust Notes | Other Securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment securities available-for-sale	90		97
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		$ 16
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities forwards
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 36
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Derivative liabilities	$ 61
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and swaptions
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 182
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Derivative liabilities	$ 65
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Futures
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 2
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage servicing rights	$ 1,033
Total assets at fair value	1,042
Total liabilities at fair value	10
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Rate lock commitments (fallout-adjusted)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative assets	$ 9
Derivative Asset, Statement of Financial Position [Extensible Enumeration]	Other Assets
Derivative liabilities	$ 10
Derivative Liability, Statement of Financial Position [Extensible Enumeration]	Other Liabilities

[1] Excludes accrued interest receivable of $31 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.