Relationship with Bayview Lending Group LLC and Bayview Financial Holdings, L.P. - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Dec. 31, 2023
Schedule of Equity Method Investments [Line Items]
Revenue from contract with customer	$ 388,000,000	$ 376,000,000	$ 755,000,000	$ 759,000,000
Loan facility carrying amount	$ 11,319,000,000		$ 11,319,000,000		$ 8,201,000,000
Bayview Lending Group
Schedule of Equity Method Investments [Line Items]
Ownership percentage (as a percent)	20.00%		20.00%
Equity method investments	$ 0		$ 0
Bayview Lending Group | Other Revenues From Operations
Schedule of Equity Method Investments [Line Items]
Income from equity method investments			25,000,000	20,000,000
Bayview Lending Group and Bayview Financial
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of mortgage servicing rights	1,100,000,000		1,100,000,000		1,200,000,000
Revenue from contract with customer	1,000,000	2,000,000	3,000,000
Bayview Financial
Schedule of Equity Method Investments [Line Items]
Outstanding principal balances of residential mortgage loans from Bayview Financial	112,500,000,000		112,500,000,000		115,300,000,000
Revenues from sub-servicing	31,000,000	$ 32,000,000	63,000,000	$ 64,000,000
Investment securities in held-to-maturity portfolio securitized by Bayview Financial	40,000,000		40,000,000		$ 42,000,000
Bayview Financial | Syndicated Loan Facility
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	3,600,000,000		3,600,000,000
Bayview Financial | Syndicated Loan Facility | M&T Bank
Schedule of Equity Method Investments [Line Items]
Loan facility carrying amount	$ 701,000,000		$ 701,000,000