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, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Assets:
Amounts received pursuant to sales of loans	$ 40,619	$ 90,747	$ 71,868	$ 191,365
Changes in fair value included in results of operations arising from:
Loans to REO			0	(803)
Mortgage servicing rights relating to delinquent loans to Agency			$ 216	$ (723)
Liabilities:
Fair Value, Asset, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Gain (Loss) on Investments	Gain (Loss) on Investments	Gain (Loss) on Investments	Gain (Loss) on Investments
Interest Rate Lock Commitments [Member]
Assets:
Beginning balance			$ 7,532
Changes in fair value included in results of operations arising from:
Ending balance	$ 1,552		1,552
Recurring [Member]
Assets:
Beginning balance	4,063,926	$ 3,870,357	3,998,787	$ 3,867,133
Purchases and issuances (purchase adjustments)	8,760	4,523	42,796	450
Repayments and sales	(21,360)	(21,992)	(44,283)	(40,971)
Accrual of unearned discounts	2,390		4,606
Amounts received pursuant to sales of loans	40,619	90,747	71,868	191,365
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	(41,926)	(41,527)	(16,564)	(104,256)
Total	(41,926)	(41,527)	(16,564)	(104,256)
Loans to REO				(460)
Interest rate lock commitments to loans acquired for sale	(3,906)	752	(8,849)	(9,566)
Mortgage servicing rights relating to delinquent loans to Agency	74	112	216	(723)
Ending balance	4,048,577	3,902,972	4,048,577	3,902,972
Changes in fair value recognized during the quarter relating to assets	(47,942)	(46,461)	(40,425)	(151,671)
Recurring [Member] \| CRT Derivatives [Member]
Assets:
Beginning balance	22,899	(13,860)	16,160	(22,098)
Purchases and issuances (purchase adjustments)	0	0	0	0
Repayments and sales	(3,633)	(5,367)	(7,084)	(8,255)
Accrual of unearned discounts	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	5,039	14,833	15,229	25,959
Total	5,039	14,833	15,229	25,959
Loans to REO				0
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	24,305	(4,394)	24,305	(4,394)
Changes in fair value recognized during the quarter relating to assets	5,039	9,410	8,256	17,506
Recurring [Member] \| Credit Risk Transfer Strips [Member]
Assets:
Beginning balance	(17,352)	(113,065)	(46,692)	(137,193)
Purchases and issuances (purchase adjustments)	0	0	0	0
Repayments and sales	(11,693)	(11,984)	(23,378)	(24,288)
Accrual of unearned discounts	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	12,071	46,480	53,096	82,912
Total	12,071	46,480	53,096	82,912
Loans to REO				0
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	(16,974)	(78,569)	(16,974)	(78,569)
Changes in fair value recognized during the quarter relating to assets	378	34,496	29,718	58,624
Recurring [Member] \| Loans At Fair Value [Member]
Assets:
Beginning balance	2,034	3,548	2,131	3,457
Purchases and issuances (purchase adjustments)	0	0	0	119
Repayments and sales	(32)	(4)	(91)	(24)
Accrual of unearned discounts	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)	(879)	(42)	(427)
Total	(4)	(879)	(42)	(427)
Loans to REO				(460)
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	1,998	2,665	1,998	2,665
Changes in fair value recognized during the quarter relating to assets	(11)	(879)	(52)	(886)
Recurring [Member] \| Mortgage servicing rights [Member]
Assets:
Beginning balance	3,951,737	3,975,076	3,919,107	4,012,737
Purchases and issuances (purchase adjustments)	(13)	0	29,428	0
Repayments and sales	0	0	0	0
Accrual of unearned discounts	0		0
Amounts received pursuant to sales of loans	40,619	90,747	71,868	191,365
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0	0	0	0
Other factors	(50,556)	(87,997)	(78,758)	(225,441)
Total	(50,556)	(87,997)	(78,758)	(225,441)
Loans to REO				0
Interest rate lock commitments to loans acquired for sale	0	0	0	0
Mortgage servicing rights relating to delinquent loans to Agency	74	112	216	(723)
Ending balance	3,941,861	3,977,938	3,941,861	3,977,938
Changes in fair value recognized during the quarter relating to assets	(50,556)	(87,997)	(78,758)	(225,441)
Recurring [Member] \| Loans acquired for sale [Member]
Assets:
Beginning balance	5,096	10,109	6,318	10,708
Purchases and issuances (purchase adjustments)	4,013	767	5,497	4,262
Repayments and sales	(1,018)	(4,637)	(3,676)	(8,404)
Accrual of unearned discounts	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	(97)	391	(145)	64
Total	(97)	391	(145)	64
Loans to REO				0
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
Ending balance	7,994	6,630	7,994	6,630
Changes in fair value recognized during the quarter relating to assets	(112)	(193)	(199)	(176)
Recurring [Member] \| Interest Rate Lock Commitments [Member]
Assets:
Beginning balance	4,845	8,549	7,532	(478)
Purchases and issuances (purchase adjustments)	4,760	3,756	7,871	(3,931)
Repayments and sales	0	0	0	0
Accrual of unearned discounts	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	(4,147)	(14,355)	(5,002)	12,677
Total	(4,147)	(14,355)	(5,002)	12,677
Loans to REO				0
Interest rate lock commitments to loans acquired for sale	(3,906)	752	(8,849)	(9,566)
Mortgage servicing rights relating to delinquent loans to Agency	0	0	0	0
Ending balance	1,552	(1,298)	1,552	(1,298)
Changes in fair value recognized during the quarter relating to assets	1,552	(1,298)	1,552	(1,298)
Recurring [Member] \| Interest-only security payable [Member]
Liabilities:
Beginning balance	32,227	23,205	32,667	21,925
Changes in instrument-specific credit risk\Other factors	481	855	41	2,135
Ending balance	32,708	24,060	32,708	24,060
Changes in fair value recognized during the quarter relating to liability	481	855	41	2,135
Recurring [Member] \| Interest-only security payable [Member] \| Credit Risk [Member]
Liabilities:
Changes in instrument-specific credit risk\Other factors	0	0	0	0
Recurring [Member] \| Interest-only security payable [Member] \| Other Factors [Member]
Liabilities:
Changes in instrument-specific credit risk\Other factors	481	$ 855	41	$ 2,135
Recurring [Member] \| Interest-Only Stripped Mortgage-Backed Securities [Member]
Assets:
Beginning balance	94,667		94,231
Purchases and issuances (purchase adjustments)	0		0
Repayments and sales	(4,984)		(10,054)
Accrual of unearned discounts	2,390		4,606
Amounts received pursuant to sales of loans	0		0
Changes in fair value included in results of operations arising from:
Changes in instrument-specific credit risk	0		0
Other factors	(4,232)		(942)
Total	(4,232)		(942)
Interest rate lock commitments to loans acquired for sale	0		0
Mortgage servicing rights relating to delinquent loans to Agency	0		0
Ending balance	87,841		87,841
Changes in fair value recognized during the quarter relating to assets	$ (4,232)		$ (942)

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Indicates line item in statement in which net income is reported that includes unrealized gain (loss) from asset measured at fair value using unobservable input (level 3) and still held.

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

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

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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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Amount of gain (loss) recognized in income from liability measured at fair value on recurring basis using unobservable input (level 3).

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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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This item represents the estimated amount of gains or losses included in earnings during the period attributable to changes in instrument-specific credit risk arising from loans and other receivables held as assets.

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Value transferred from mortgage loans to real estate owned (REO) in noncash transactions.

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