Fair Value - Summary of Changes in Items Measured Using Level 3 Inputs on Recurring Basis (Detail) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2025	Jun. 30, 2024
Assets:
Amounts received pursuant to sales of loans	$ 44,030	$ 40,619	$ 91,039	$ 71,868
Changes in fair value included in results of operations arising from:
Mortgage servicing rights relating to delinquent loans to Agency			391	216
Interest Rate Lock Commitments [Member]
Assets:
Beginning balance			444
Changes in fair value included in results of operations arising from:
Ending balance	6,485		6,485
Recurring [Member]
Assets:
Beginning balance	3,875,551	4,063,926	3,989,252	3,998,787
Purchases and issuances (purchase adjustment)	6,656	8,760	11,283	42,796
Repayments and sales	(18,854)	(21,360)	(38,848)	(44,283)
Accrual of unearned discounts	2,165	2,390	4,450	4,606
Amounts received pursuant to sales of loans	44,030	40,619	91,039	71,868
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	(49,172)	(41,926)	(189,206)	(16,564)
Total	(49,172)	(41,926)	(189,206)	(16,564)
Interest rate lock commitments to loans acquired for sale	(6,216)	(3,906)	(14,031)	(8,849)
Mortgage servicing rights relating to delinquent loans to Agency	170	74	391	216
Ending balance	3,854,330	4,048,577	3,854,330	4,048,577
Changes in fair value recognized during the quarter/period relating to assets	(60,046)	(47,942)	(220,141)	(40,425)
Recurring [Member] \| CRT Derivatives [Member]
Assets:
Beginning balance	28,474	22,899	29,377	16,160
Purchases and issuances (purchase adjustment)	0	0	0	0
Repayments and sales	(2,702)	(3,633)	(5,585)	(7,084)
Accrual of unearned discounts	0	0	0	0
Amounts received pursuant to sales of loans	0	0	0	0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	5,375	5,039	7,355	15,229
Total	5,375	5,039	7,355	15,229
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	31,147	24,305	31,147	24,305
Changes in fair value recognized during the quarter/period relating to assets	2,743	5,039	1,920	8,256
Recurring [Member] \| Credit Risk Transfer Strips [Member]
Assets:
Beginning balance	(15,885)	(17,352)	(4,060)	(46,692)
Purchases and issuances (purchase adjustment)	0	0	0	0
Repayments and sales	(10,068)	(11,693)	(19,845)	(23,378)
Accrual of unearned discounts	0	0	0	0
Amounts received pursuant to sales of loans	0	0	0	0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	15,474	12,071	13,426	53,096
Total	15,474	12,071	13,426	53,096
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	(10,479)	(16,974)	(10,479)	(16,974)
Changes in fair value recognized during the quarter/period relating to assets	5,524	378	(6,301)	29,718
Recurring [Member] \| Loans Held for Investment [Member]
Assets:
Beginning balance	1,815	2,034	1,866	2,131
Purchases and issuances (purchase adjustment)	0	0	0	0
Repayments and sales	(20)	(32)	(40)	(91)
Accrual of unearned discounts	0	0	0	0
Amounts received pursuant to sales of loans	0	0	0	0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	59	(4)	28	(42)
Total	59	(4)	28	(42)
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	1,854	1,998	1,854	1,998
Changes in fair value recognized during the quarter/period relating to assets	58	(11)	27	(52)
Recurring [Member] \| Mortgage servicing rights [Member]
Assets:
Beginning balance	3,770,034	3,951,737	3,867,394	3,919,107
Purchases and issuances (purchase adjustment)	0	(13)	0	29,428
Repayments and sales	0	0	0	0
Accrual of unearned discounts	0	0	0	0
Amounts received pursuant to sales of loans	44,030	40,619	91,039	71,868
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	(75,128)	(50,556)	(219,718)	(78,758)
Total	(75,128)	(50,556)	(219,718)	(78,758)
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	170	74	391	216
Ending balance	3,739,106	3,941,861	3,739,106	3,941,861
Changes in fair value recognized during the quarter/period relating to assets	(75,128)	(50,556)	(219,718)	(78,758)
Recurring [Member] \| Loans acquired for sale [Member]
Assets:
Beginning balance	5,451	5,096	7,971	6,318
Purchases and issuances (purchase adjustment)	3,103	4,013	3,131	5,497
Repayments and sales	(1,540)	(1,018)	(4,218)	(3,676)
Accrual of unearned discounts	0	0	0	0
Amounts received pursuant to sales of loans	0	0	0	0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	151	(97)	281	(145)
Total	151	(97)	281	(145)
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	7,165	7,994	7,165	7,994
Changes in fair value recognized during the quarter/period relating to assets	(96)	(112)	(56)	(199)
Recurring [Member] \| Interest Rate Lock Commitments [Member]
Assets:
Beginning balance	4,619	4,845	444	7,532
Purchases and issuances (purchase adjustment)	3,553	4,760	8,152	7,871
Repayments and sales	0	0	0	0
Accrual of unearned discounts	0	0	0	0
Amounts received pursuant to sales of loans	0	0	0	0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	4,529	(4,147)	11,920	(5,002)
Total	4,529	(4,147)	11,920	(5,002)
Interest rate lock commitments to loans acquired for sale	(6,216)	(3,906)	(14,031)	(8,849)
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	6,485	1,552	6,485	1,552
Changes in fair value recognized during the quarter/period relating to assets	6,485	1,552	6,485	1,552
Recurring [Member] \| Interest-only security payable [Member]
Liabilities:
Beginning balance	35,954	32,227	34,222	32,667
Changes in instrument-specific credit risk\Other factors	599	481	2,331	41
Ending balance	36,553	32,708	36,553	32,708
Changes in fair value recognized during the quarter/period relating to liability	599	481	2,331	41
Recurring [Member] \| Interest-only security payable [Member] \| Credit Risk [Member]
Liabilities:
Changes in instrument-specific credit risk\Other factors	0	0	0
Recurring [Member] \| Interest-only security payable [Member] \| Other Factors [Member]
Liabilities:
Changes in instrument-specific credit risk\Other factors	599	481	2,331	41
Recurring [Member] \| Interest-Only Stripped Mortgage-Backed Securities [Member]
Assets:
Beginning balance	81,043	94,667	86,260	94,231
Purchases and issuances (purchase adjustment)	0	0	0	0
Repayments and sales	(4,524)	(4,984)	(9,160)	(10,054)
Accrual of unearned discounts	2,165	2,390	4,450	4,606
Amounts received pursuant to sales of loans	0	0	0	0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	368	(4,232)	(2,498)	(942)
Total	368	(4,232)	(2,498)	(942)
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	79,052	87,841	79,052	87,841
Changes in fair value recognized during the quarter/period relating to assets	$ 368	$ (4,232)	$ (2,498)	$ (942)

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Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3) and still held.

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Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

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