Fair Value Measures - Financial Instruments Carried at Fair Value (Details) - USD ($) $ in Millions	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023
Assets:
Loans held for sale	$ 1,451	$ 902
Mortgage servicing rights	1,122	1,111	$ 1,031
Total debt securities available for sale
Assets:
Total debt securities available for sale	10,535	9,145
Mortgage-related Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	8,451	6,563
GSE certificates
Assets:
Total debt securities available for sale	1,153	1,221
GSE collateralized mortgage obligations
Assets:
Total debt securities available for sale	7,130	5,162
Private label collateralized mortgage obligations
Assets:
Total debt securities available for sale	168	180
Other Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	2,084	2,582
U. S. Treasury obligations
Assets:
Total debt securities available for sale	0	198
GSE debentures
Assets:
Total debt securities available for sale	1,344	1,609
Asset-backed securities
Assets:
Total debt securities available for sale	269	302
Municipal bonds
Assets:
Total debt securities available for sale	6	6
Corporate bonds
Assets:
Total debt securities available for sale	341	343
Foreign notes
Assets:
Total debt securities available for sale	35	34
Capital trust notes
Assets:
Total debt securities available for sale	89	90
Recurring
Assets:
Total securities	10,549	9,159
Mortgage servicing rights	1,122	1,111
Total assets at fair value	13,319	11,310
Liabilities:
Total liabilities at fair value	77	95
Recurring | Acquisition, development, and construction
Assets:
Loans held for sale	158	123
Recurring | Commercial and industrial
Assets:
Loans held for sale	34	9
Recurring | Loans and Leases Held for Investment: | Residential first mortgage loans
Assets:
Loans held for sale	1,259	770
Loans held-for-investment	68
Recurring | Interest rate swaps and swaptions
Assets:
Derivative assets	111	115
Liabilities:
Derivative liabilities	63	59
Recurring | Futures
Liabilities:
Derivative liabilities		1
Recurring | Rate lock commitments
Assets:
Derivative assets	9	12
Liabilities:
Derivative liabilities	5	3
Recurring | Mortgage-backed securities forwards
Assets:
Derivative assets	9	11
Liabilities:
Derivative liabilities	9	32
Recurring | Total debt securities available for sale
Assets:
Total debt securities available for sale	10,535	9,145
Recurring | Mortgage-related Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	8,451	6,563
Recurring | GSE certificates
Assets:
Total debt securities available for sale	1,153	1,221
Recurring | GSE collateralized mortgage obligations
Assets:
Total debt securities available for sale	7,130	5,162
Recurring | Private label collateralized mortgage obligations
Assets:
Total debt securities available for sale	168	180
Recurring | Other Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	2,084	2,582
Recurring | U. S. Treasury obligations
Assets:
Total debt securities available for sale		198
Recurring | GSE debentures
Assets:
Total debt securities available for sale	1,344	1,609
Recurring | Asset-backed securities
Assets:
Total debt securities available for sale	269	302
Recurring | Municipal bonds
Assets:
Total debt securities available for sale	6	6
Recurring | Corporate bonds
Assets:
Total debt securities available for sale	341	343
Recurring | Foreign notes
Assets:
Total debt securities available for sale	35	34
Recurring | Capital trust notes
Assets:
Total debt securities available for sale	89	90
Recurring | Equity securities:
Assets:
Equity securities:	14	14
Recurring | Mutual funds and common stock
Assets:
Equity securities:	14	14
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Assets:
Total securities	0	198
Mortgage servicing rights	0	0
Total assets at fair value	0	198
Liabilities:
Total liabilities at fair value	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Acquisition, development, and construction
Assets:
Loans held for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Commercial and industrial
Assets:
Loans held for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Loans and Leases Held for Investment: | Residential first mortgage loans
Assets:
Loans held for sale	0	0
Loans held-for-investment	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Interest rate swaps and swaptions
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Futures
Liabilities:
Derivative liabilities
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	0
Liabilities:
Derivative liabilities	0	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	0	198
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mortgage-related Debt Securities Available for Sale:
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) | GSE collateralized mortgage obligations
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) | Other Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	0	198
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | U. S. Treasury obligations
Assets:
Total debt securities available for sale		198
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) | 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
Assets:
Total debt securities available for sale	0	0
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) | Foreign notes
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Capital trust notes
Assets:
Total debt securities available for sale	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Equity securities:
Assets:
Equity securities:	0	0
Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Mutual funds and common stock
Assets:
Equity securities:	0	0
Recurring | Significant Other Observable Inputs (Level 2)
Assets:
Total securities	10,516	8,929
Mortgage servicing rights	0	0
Total assets at fair value	12,155	9,957
Liabilities:
Total liabilities at fair value	72	92
Recurring | Significant Other Observable Inputs (Level 2) | Acquisition, development, and construction
Assets:
Loans held for sale	158	123
Recurring | Significant Other Observable Inputs (Level 2) | Commercial and industrial
Assets:
Loans held for sale	34	9
Recurring | Significant Other Observable Inputs (Level 2) | Loans and Leases Held for Investment: | Residential first mortgage loans
Assets:
Loans held for sale	1,259	770
Loans held-for-investment	68
Recurring | Significant Other Observable Inputs (Level 2) | Interest rate swaps and swaptions
Assets:
Derivative assets	111	115
Liabilities:
Derivative liabilities	63	59
Recurring | Significant Other Observable Inputs (Level 2) | Futures
Liabilities:
Derivative liabilities		1
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	9	11
Liabilities:
Derivative liabilities	9	32
Recurring | Significant Other Observable Inputs (Level 2) | Total debt securities available for sale
Assets:
Total debt securities available for sale	10,502	8,915
Recurring | Significant Other Observable Inputs (Level 2) | Mortgage-related Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	8,418	6,531
Recurring | Significant Other Observable Inputs (Level 2) | GSE certificates
Assets:
Total debt securities available for sale	1,153	1,221
Recurring | Significant Other Observable Inputs (Level 2) | GSE collateralized mortgage obligations
Assets:
Total debt securities available for sale	7,130	5,162
Recurring | Significant Other Observable Inputs (Level 2) | Private label collateralized mortgage obligations
Assets:
Total debt securities available for sale	135	148
Recurring | Significant Other Observable Inputs (Level 2) | Other Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	2,084	2,384
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) | GSE debentures
Assets:
Total debt securities available for sale	1,344	1,609
Recurring | Significant Other Observable Inputs (Level 2) | Asset-backed securities
Assets:
Total debt securities available for sale	269	302
Recurring | Significant Other Observable Inputs (Level 2) | Municipal bonds
Assets:
Total debt securities available for sale	6	6
Recurring | Significant Other Observable Inputs (Level 2) | Corporate bonds
Assets:
Total debt securities available for sale	341	343
Recurring | Significant Other Observable Inputs (Level 2) | Foreign notes
Assets:
Total debt securities available for sale	35	34
Recurring | Significant Other Observable Inputs (Level 2) | Capital trust notes
Assets:
Total debt securities available for sale	89	90
Recurring | Significant Other Observable Inputs (Level 2) | Equity securities:
Assets:
Equity securities:	14	14
Recurring | Significant Other Observable Inputs (Level 2) | Mutual funds and common stock
Assets:
Equity securities:	14	14
Recurring | Significant Unobservable Inputs (Level 3)
Assets:
Total securities	33	32
Mortgage servicing rights	1,122	1,111
Total assets at fair value	1,164	1,155
Liabilities:
Total liabilities at fair value	5	3
Recurring | Significant Unobservable Inputs (Level 3) | Acquisition, development, and construction
Assets:
Loans held for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Commercial and industrial
Assets:
Loans held for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Loans and Leases Held for Investment: | Residential first mortgage loans
Assets:
Loans held for sale	0	0
Loans held-for-investment	0
Recurring | Significant Unobservable Inputs (Level 3) | Interest rate swaps and swaptions
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Futures
Liabilities:
Derivative liabilities
Recurring | Significant Unobservable Inputs (Level 3) | Rate lock commitments
Assets:
Derivative assets	9	12
Liabilities:
Derivative liabilities	5	3
Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-backed securities forwards
Assets:
Derivative assets	0	0
Liabilities:
Derivative liabilities	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Total debt securities available for sale
Assets:
Total debt securities available for sale	33	32
Recurring | Significant Unobservable Inputs (Level 3) | Mortgage-related Debt Securities Available for Sale:
Assets:
Total debt securities available for sale	33	32
Recurring | Significant Unobservable Inputs (Level 3) | GSE certificates
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | GSE collateralized mortgage obligations
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	33	32
Recurring | Significant Unobservable Inputs (Level 3) | Other Debt Securities Available for Sale:
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) | GSE debentures
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
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Corporate bonds
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Foreign notes
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Capital trust notes
Assets:
Total debt securities available for sale	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Equity securities:
Assets:
Equity securities:	0	0
Recurring | Significant Unobservable Inputs (Level 3) | Mutual funds and common stock
Assets:
Equity securities:	$ 0	$ 0