Assets Sold Under Agreements to Repurchase - Summary of Assets Sold under Agreements to Repurchase by Counterparty (Detail) $ in Thousands	9 Months Ended
	Sep. 30, 2024 USD ($)
Goldman Sachs & Co. LLC [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 94,042
Weighted-average maturity, Advances	Dec. 23, 2024
Weighted-average maturity, Facility	Jan. 26, 2026
Goldman Sachs & Co. LLC [Member] | Credit Risk Transfer Agreements [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 22,378
Weighted average maturity	Jan. 08, 2025
Citibank, N.A. [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 45,724
Weighted average maturity	Dec. 27, 2024
Citibank, N.A. [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 44,524
Weighted-average maturity, Advances	Nov. 09, 2024
Weighted-average maturity, Facility	Jun. 11, 2026
Bank of America, N.A. [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 29,249
Weighted average maturity	Nov. 14, 2024
Bank of America, N.A. [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 43,142
Weighted-average maturity, Advances	Oct. 11, 2024
Weighted-average maturity, Facility	Jun. 10, 2026
JPMorgan Chase & Co. [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 58,000
Weighted average maturity	Nov. 11, 2024
JPMorgan Chase & Co. [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 10,946
Weighted-average maturity, Advances	Nov. 09, 2024
Weighted-average maturity, Facility	Jun. 28, 2026
Atlas Securitized Products, L.P. [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 51,541
Weighted-average maturity, Advances	Nov. 24, 2024
Weighted-average maturity, Facility	Jun. 26, 2026
Wells Fargo Securities L L C [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 33,220
Weighted average maturity	Jan. 23, 2025
Wells Fargo Securities L L C [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 7,448
Weighted-average maturity, Advances	Dec. 19, 2024
Weighted-average maturity, Facility	Oct. 15, 2025
Barclays Capital Inc. [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 24,401
Weighted average maturity	Nov. 27, 2024
Barclays Capital Inc. [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 10,112
Weighted-average maturity, Advances	Dec. 23, 2024
Weighted-average maturity, Facility	Mar. 06, 2026
Santander US Capital [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 19,410
Weighted average maturity	Dec. 23, 2024
Daiwa Capital Markets America Inc. [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 6,617
Weighted average maturity	Jan. 02, 2025
Mizuho Financial Group [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 5,448
Weighted average maturity	Jan. 06, 2025
RBC Capital Markets L.P. [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 10,722
Weighted-average maturity, Advances	Jan. 01, 2025
Weighted-average maturity, Facility	Aug. 11, 2025
Morgan Stanley & Co. LLC [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 9,549
Weighted-average maturity, Advances	Dec. 19, 2024
Weighted-average maturity, Facility	May 22, 2026
BNP Paribas [Member] | Mortgage loans acquired for sale, mortgage loans, REO and MSRs sold under agreements to repurchase [Member]
Assets Sold under Agreements to Repurchase [Line Items]
Amount at risk	$ 3,207
Weighted-average maturity, Advances	Dec. 23, 2024
Weighted-average maturity, Facility	Sep. 30, 2025