Fair Value Measures - Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2025	Dec. 31, 2024
Assets:
Total debt securities available for sale	$ 12,826	$ 10,402
Total mortgage-related debt securities
Assets:
Total debt securities available for sale	10,016	8,573
GSE CMOs
Assets:
Total debt securities available for sale	8,744	7,304
GSE certificates
Assets:
Total debt securities available for sale	1,110	1,106
Private Label collateralized mortgage obligations
Assets:
Total debt securities available for sale	162	163
Total other debt securities
Assets:
Total debt securities available for sale	2,810	1,829
GSE debentures
Assets:
Total debt securities available for sale	1,241	1,203
U. S. Treasury obligations
Assets:
Total debt securities available for sale	1,008
Corporate bonds
Assets:
Total debt securities available for sale	249	308
Asset-backed securities
Assets:
Total debt securities available for sale	229	236
Municipal bonds, foreign notes, and capital trust
Assets:
Total debt securities available for sale	5	5
Recurring
Assets:
Total securities	12,840	10,416
Mortgage servicing rights		26
Total assets at fair value	13,367	11,031
Liabilities:
Total liabilities at fair value	29	35
Recurring | Interest rate swaps
Assets:
Derivative assets	15	15
Liabilities:
Derivative liabilities	23
Recurring | Interest rate swaps and swaptions
Liabilities:
Derivative liabilities		30
Recurring | Rate lock commitments
Assets:
Derivative assets	4	3
Liabilities:
Derivative liabilities	3	3
Recurring | Mortgage-backed securities forwards
Assets:
Derivative assets		7
Liabilities:
Derivative liabilities	3	2
Recurring | Multi-family
Assets:
Loans held for sale	328	382
Recurring | Commercial real estate
Assets:
Loans held for sale	180
Recurring | Acquisition, development, and construction
Assets:
Loans held for sale		182
Recurring | Total debt securities available for sale
Assets:
Total debt securities available for sale	12,826	10,402
Recurring | Total mortgage-related debt securities
Assets:
Total debt securities available for sale	10,016	8,573
Recurring | GSE CMOs
Assets:
Total debt securities available for sale	8,744	7,304
Recurring | GSE certificates
Assets:
Total debt securities available for sale	1,110	1,106
Recurring | Private Label collateralized mortgage obligations
Assets:
Total debt securities available for sale	162	163
Recurring | Total other debt securities
Assets:
Total debt securities available for sale	2,810	1,829
Recurring | GSE debentures
Assets:
Total debt securities available for sale	1,241	1,203
Recurring | U. S. Treasury obligations
Assets:
Total debt securities available for sale	1,008
Recurring | Corporate bonds
Assets:
Total debt securities available for sale	249	308
Recurring | Asset-backed securities
Assets:
Total debt securities available for sale	229	236
Recurring | Municipal bonds, foreign notes, and capital trust
Assets:
Total debt securities available for sale	83	82
Recurring | Total equity securities
Assets:
Total equity securities	14	14
Recurring | Mutual funds and common stock
Assets:
Total equity securities	14	14
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total securities	1,008	0
Mortgage servicing rights		0
Total assets at fair value	1,008	0
Liabilities:
Total liabilities at fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps and swaptions
Liabilities:
Derivative liabilities		0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Rate lock commitments
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-backed securities forwards
Assets:
Derivative assets		0
Liabilities:
Derivative liabilities	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Multi-family
Assets:
Loans held for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial real estate
Assets:
Loans held for sale	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Acquisition, development, and construction
Assets:
Loans held for sale		0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total debt securities available for sale
Assets:
Total debt securities available for sale	1,008	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total mortgage-related debt securities
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | GSE CMOs
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | GSE certificates
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Private Label collateralized mortgage obligations
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total other debt securities
Assets:
Total debt securities available for sale	1,008	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | GSE debentures
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U. S. Treasury obligations
Assets:
Total debt securities available for sale	1,008
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate bonds
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Asset-backed securities
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Municipal bonds, foreign notes, and capital trust
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Total equity securities
Assets:
Total equity securities	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds and common stock
Assets:
Total equity securities	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Total securities	11,801	10,383
Mortgage servicing rights		0
Total assets at fair value	12,324	10,969
Liabilities:
Total liabilities at fair value	26	32
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps
Assets:
Derivative assets	15	15
Liabilities:
Derivative liabilities	23
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and swaptions
Liabilities:
Derivative liabilities		30
Recurring | Significant Other Observable Inputs (Level 2) | Rate lock commitments
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	0
Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-backed securities forwards
Assets:
Derivative assets		7
Liabilities:
Derivative liabilities	3	2
Recurring | Significant Other Observable Inputs (Level 2) | Multi-family
Assets:
Loans held for sale	328	382
Recurring | Significant Other Observable Inputs (Level 2) | Commercial real estate
Assets:
Loans held for sale	180
Recurring | Significant Other Observable Inputs (Level 2) | Acquisition, development, and construction
Assets:
Loans held for sale		182
Recurring | Significant Other Observable Inputs (Level 2) | Total debt securities available for sale
Assets:
Total debt securities available for sale	11,787	10,369
Recurring | Significant Other Observable Inputs (Level 2) | Total mortgage-related debt securities
Assets:
Total debt securities available for sale	9,985	8,540
Recurring | Significant Other Observable Inputs (Level 2) | GSE CMOs
Assets:
Total debt securities available for sale	8,744	7,304
Recurring | Significant Other Observable Inputs (Level 2) | GSE certificates
Assets:
Total debt securities available for sale	1,110	1,106
Recurring | Significant Other Observable Inputs (Level 2) | Private Label collateralized mortgage obligations
Assets:
Total debt securities available for sale	131	130
Recurring | Significant Other Observable Inputs (Level 2) | Total other debt securities
Assets:
Total debt securities available for sale	1,802	1,829
Recurring | Significant Other Observable Inputs (Level 2) | GSE debentures
Assets:
Total debt securities available for sale	1,241	1,203
Recurring | Significant Other Observable Inputs (Level 2) | U. S. Treasury obligations
Assets:
Total debt securities available for sale	0
Recurring | Significant Other Observable Inputs (Level 2) | Corporate bonds
Assets:
Total debt securities available for sale	249	308
Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Assets:
Total debt securities available for sale	229	236
Recurring | Significant Other Observable Inputs (Level 2) | Municipal bonds, foreign notes, and capital trust
Assets:
Total debt securities available for sale	83	82
Recurring | Significant Other Observable Inputs (Level 2) | Total equity securities
Assets:
Total equity securities	14	14
Recurring | Significant Other Observable Inputs (Level 2) | Mutual funds and common stock
Assets:
Total equity securities	14	14
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Total securities	31	33
Mortgage servicing rights		26
Total assets at fair value	35	62
Liabilities:
Total liabilities at fair value	3	3
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swaps
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swaps and swaptions
Liabilities:
Derivative liabilities		0
Recurring | Significant Unobservable Inputs (Level 3) | Rate lock commitments
Assets:
Derivative assets	4	3
Liabilities:
Derivative liabilities	3	3
Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities forwards
Assets:
Derivative assets		0
Liabilities:
Derivative liabilities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Multi-family
Assets:
Loans held for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Commercial real estate
Assets:
Loans held for sale	0
Recurring | Significant Unobservable Inputs (Level 3) | Acquisition, development, and construction
Assets:
Loans held for sale		0
Recurring | Significant Unobservable Inputs (Level 3) | Total debt securities available for sale
Assets:
Total debt securities available for sale	31	33
Recurring | Significant Unobservable Inputs (Level 3) | Total mortgage-related debt securities
Assets:
Total debt securities available for sale	31	33
Recurring | Significant Unobservable Inputs (Level 3) | GSE CMOs
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | GSE certificates
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Private Label collateralized mortgage obligations
Assets:
Total debt securities available for sale	31	33
Recurring | Significant Unobservable Inputs (Level 3) | Total other debt securities
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | GSE debentures
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | U. S. Treasury obligations
Assets:
Total debt securities available for sale	0
Recurring | Significant Unobservable Inputs (Level 3) | Corporate bonds
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Asset-backed securities
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Municipal bonds, foreign notes, and capital trust
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Total equity securities
Assets:
Total equity securities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Mutual funds and common stock
Assets:
Total equity securities	$ 0	$ 0