Borrowings - Mortgage Loan Participation and Sale Agreement (Details) - USD ($)	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
During the period:
Total interest expense	$ 2,304,000	$ 2,533,000	$ 7,034,000	$ 6,450,000
Carrying value:
Mortgage loan participation and sale agreement secured by mortgage loan participation certificates	514,625,000		514,625,000		$ 532,251,000
Fair value of loans pledged to secure	542,049,000		542,049,000		555,001,000
Mortgage Loan Participation and Sale Agreement member
During the period:
Average balance	$ 258,169,000	$ 289,008,000	$ 249,023,000	$ 250,599,000
Short-term Debt, Weighted Average Interest Rate, over Time	3.36%	3.31%	3.55%	3.14%
Total interest expense	$ 2,304,000	$ 2,533,000	$ 7,034,000	$ 6,450,000
Carrying value:
Unpaid principal balance of mortgage loan participation and sale agreement secured by mortgage loan participation certificates	514,625,000		514,625,000		532,466,000
Unamortized issuance costs					(215,000)
Mortgage loan participation and sale agreement secured by mortgage loan participation certificates	$ 514,625.00		$ 514,625.00		$ 532,251.00
Weighted average interest rate (as a percent)	3.27%		3.27%		3.77%
Fair value of loans pledged to secure	$ 542,049,000		$ 542,049,000		$ 555,001,000
Amortization of debt issuance costs	135,000	92,000	405,000	475,000
Maximum \| Mortgage Loan Participation and Sale Agreement member
Carrying value:
Mortgage loan participation and sale agreement secured by mortgage loan participation certificates	$ 524,095,000	$ 722,611,000	$ 548,038,000	$ 722,611,000

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

No definition available.

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Namespace Prefix:	pfsi_
Data Type:	xbrli:monetaryItemType
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Period Type:	duration

- 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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Namespace Prefix:	pfsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

No definition available.

+ Details

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Namespace Prefix:	pfsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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- Definition

+ References

No definition available.

+ Details

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- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
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- References

No definition available.

+ Details

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- Definition

The sum of the carrying amounts, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of related debt obligations, and for which the transferees are not permitted to sell or re-pledge them to an unrelated party.

+ References

No definition available.

+ Details

Name:	pfsi_PledgedFinancialInstrumentsNotSeparatelyReportedLoansReceivablePledgedAsCollateralForParticipatingAndSaleAgreement
Namespace Prefix:	pfsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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 http://asc.fasb.org/extlink&oid=118932676&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 http://asc.fasb.org/extlink&oid=116634182&loc=SL114868664-224227

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28555-108399

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

- 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 http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Data Type:	num:percentItemType
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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:	num: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

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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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

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 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Period Type:	instant

- Details

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