Short-Term Debt - Mortgage Loan Participation and Sale Agreement (Details) - USD ($)	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Carrying value:
Loans held for sale	$ 6,772,423,000		$ 3,509,300,000
Mortgage loan participation and sale agreement secured by mortgage loan participation certificates	515,358,000		287,592,000
Mortgage Loan Participation and Sale Agreement member
During the period:
Average balance	$ 184,193,000	$ 223,347,000
Weighted-average interest rate (as a percent)	6.06%	1.72%
Total interest expense	$ 2,923,000	$ 1,120,000
Carrying value:
Unpaid principal balance of mortgage loan participation and sale agreement secured by mortgage loan participation certificates	515,537,000		287,943,000
Unamortized debt issuance costs	(179,000)		(351,000)
Mortgage loan participation and sale agreement secured by mortgage loan participation certificates	$ 515,358,000		$ 287,592,000
Weighted average interest rate (as a percent)	6.15%		5.71%
Amortization of debt issuance costs	$ 172,000	172,000
Mortgage Loan Participation and Sale Agreement member \| Maximum
Carrying value:
Mortgage loan participation and sale agreement secured by mortgage loan participation certificates	515,537,000	515,043,000
Note Payable
Carrying value:
Unamortized debt issuance costs	(8,070,000)		$ (7,354,000)
Amortization of debt issuance costs	932,000	$ 459,000
Asset Pledged as Collateral without Right
Carrying value:
Loans held for sale	6,668,418,000		3,442,847,000
Asset Pledged as Collateral without Right \| Mortgage Loan Participation and Sale Agreement member
Carrying value:
Loans held for sale	543,432,000		302,977,000
Asset Pledged as Collateral without Right \| Mortgage Loan Participation and Sale Agreement member \| Mortgage Loan Participation and Sale Agreement member
Carrying value:
Loans held for sale	$ 543,432,000		$ 302,977,000

Represents the interest expense related to mortgage loans participation and sale agreement.

No definition available.

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- Definition

Participation certificates in mortgage loans that have been pooled with Fannie Mae, Freddie Mac or Ginnie Mae, are issued to a lender pending the securitization of the mortgage loans and sale of the resulting securities.

+ References

No definition available.

+ Details

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- Definition

Amount of unpaid principal balance of mortgage loan participation and sale agreement

+ References

No definition available.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

+ References

No definition available.

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- References

No definition available.

+ Details

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- References

No definition available.

+ Details

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- Definition

Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126954810&loc=d3e3602-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 220
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(8))
-URI https://asc.fasb.org/extlink&oid=126953954&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1F
-Subparagraph (b)(2)
-URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495355-112611

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28555-108399

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Fair value portion of mortgage loans held-for-sale.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Weighted average interest rate of short-term debt outstanding calculated at point in time.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Namespace Prefix:	us-gaap_
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Balance Type:	na
Period Type:	instant

- Definition

Weighted average interest rate of short-term debt outstanding calculated over time.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

For the form of debt having an initial term of less than one year or less than the normal operating cycle, if longer, average borrowings during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (a)

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher SEC
-Name Regulation S-K (SK)
-Number 229
-Section 1402
-Paragraph (b)
-Subparagraph (1)

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- Definition

The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

No definition available.

+ Details

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- Details

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- Details

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- Details

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