v3.26.1
Fair Value - Summary of Changes in Fair Value Included in Current Period Results of Operations (Detail) - USD ($)
$ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2026
Jun. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Credit Risk Transfer Strips [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) $ 7,519 $ 15,474 $ 17,880 $ 13,426
Credit Risk Transfer Strips [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 (0) 0 0
Credit Risk Transfer Strips [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Credit Risk Transfer Strips [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 7,519 15,474 17,880 13,426
Credit Risk Transfer Strips [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Interest-only security payable [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (67) (599) 3,351 (2,331)
Interest-only security payable [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Interest-only security payable [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Interest-only security payable [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (67) (599) 3,351 (2,331)
Interest-only security payable [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Asset-backed financings of VIEs [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 39,833 (14,288) 106,000 (42,343)
Asset-backed financings of VIEs [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Asset-backed financings of VIEs [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Asset-backed financings of VIEs [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 40,652 (14,793) 102,888 (44,216)
Asset-backed financings of VIEs [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (819) 505 3,112 1,873
Liabilities, Total [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 39,766 (14,887) 109,351 (44,674)
Liabilities, Total [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Liabilities, Total [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Liabilities, Total [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 40,585 (15,392) 106,239 (46,547)
Liabilities, Total [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (819) 505 3,112 1,873
Mortgage Backed Securities [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 10,030 22,146 (14,977) 97,071
Mortgage Backed Securities [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage Backed Securities [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage Backed Securities [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 426 14,564 (32,981) 79,419
Mortgage Backed Securities [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 9,604 7,582 18,004 17,652
Loans held for sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 29,400 34,080 28,981 80,591
Loans held for sale [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for sale [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 29,400 34,080 28,981 80,591
Loans held for sale [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for sale [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for investment [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (45,057) 10,171 (120,084) 38,165
Loans held for investment [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for investment [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for investment [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (28,488) 13,659 (94,291) 42,340
Loans held for investment [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (16,569) (3,488) (25,793) (4,175)
Mortgage servicing rights [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (81,464) (75,128) (142,763) (219,718)
Mortgage servicing rights [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (81,464) (75,128) (142,763) (219,718)
Mortgage servicing rights [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage servicing rights [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage servicing rights [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Assets, Total [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (79,572) 6,743 (230,963) 9,535
Assets, Total [Member] | Net Loan Servicing Fees [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (81,464) (75,128) (142,763) (219,718)
Assets, Total [Member] | Net Gains on Loans Held for Sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 29,400 34,080 28,981 80,591
Assets, Total [Member] | Net Gains (Losses) on Investments and Financings [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (20,543) 43,697 (109,392) 135,185
Assets, Total [Member] | Net Interest Expense [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) $ (6,965) $ 4,094 $ (7,789) $ 13,477