Document and Entity Information - shares	6 Months Ended
Jun. 30, 2025	Jul. 28, 2025
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2025
Document Fiscal Year Focus	2025
Document Fiscal Period Focus	Q2
Entity Registrant Name	PennyMac Mortgage Investment Trust
Entity Central Index Key	0001464423
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		87,016,604
Entity File Number	001-34416
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	27-0186273
Entity Address, Address Line One	3043 Townsgate Road
Entity Address, City or Town	Westlake Village
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	91361
City Area Code	818
Local Phone Number	224-7442
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Common Stock [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	Common Shares of Beneficial Interest, $0.01 Par Value
Trading Symbol	PMT
Security Exchange Name	NYSE
8.125% Series A Preferred Stock [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	8.125% Series A Cumulative Redeemable PreferredShares of Beneficial Interest, $0.01 Par Value
Trading Symbol	PMT/PRA
Security Exchange Name	NYSE
8.00% Series B Preferred Stock [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	8.00% Series B Cumulative Redeemable PreferredShares of Beneficial Interest, $0.01 Par Value
Trading Symbol	PMT/PRB
Security Exchange Name	NYSE
6.75% Series C Preferred Stock [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	6.75% Series C Cumulative Redeemable PreferredShares of Beneficial Interest, $0.01 Par Value
Trading Symbol	PMT/PRC
Security Exchange Name	NYSE
8.50% Senior Note Due 2028 [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	8.50% Senior Note Due September 2028
Trading Symbol	PMTU
Security Exchange Name	NYSE
9.00% Senior Notes Due 2030 [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	9.00% Senior Notes Due February 2030
Trading Symbol	PMTV
Security Exchange Name	NYSE
9.00% Senior Notes Due 2030 [Member]
Document And Entity Information [Line Items]
Title of 12(b) Security	9.00% Senior Notes Due June 2030
Trading Symbol	PMTW
Security Exchange Name	NYSE

Boolean flag that is true when the XBRL content amends previously-filed or accepted submission.

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Area code of city

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End date of current fiscal year in the format --MM-DD.

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This is focus fiscal year of the document report in YYYY format. For a 2006 annual report, which may also provide financial information from prior periods, fiscal 2006 should be given as the fiscal year focus. Example: 2006.

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For the EDGAR submission types of Form 8-K: the date of the report, the date of the earliest event reported; for the EDGAR submission types of Form N-1A: the filing date; for all other submission types: the end of the reporting or transition period. The format of the date is YYYY-MM-DD.

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Boolean flag that is true only for a form used as an quarterly report.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The type of document being provided (such as 10-K, 10-Q, 485BPOS, etc). The document type is limited to the same value as the supporting SEC submission type, or the word 'Other'.

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Address Line 1 such as Attn, Building Name, Street Name

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Name of the City or Town

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Code for the postal or zip code

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Name of the state or province.

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A unique 10-digit SEC-issued value to identify entities that have filed disclosures with the SEC. It is commonly abbreviated as CIK.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Indicate number of shares or other units outstanding of each of registrant's classes of capital or common stock or other ownership interests, if and as stated on cover of related periodic report. Where multiple classes or units exist define each class/interest by adding class of stock items such as Common Class A [Member], Common Class B [Member] or Partnership Interest [Member] onto the Instrument [Domain] of the Entity Listings, Instrument.

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Indicate 'Yes' or 'No' whether registrants (1) have filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that registrants were required to file such reports), and (2) have been subject to such filing requirements for the past 90 days. This information should be based on the registrant's current or most recent filing containing the related disclosure.

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Indicate if registrant meets the emerging growth company criteria.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Commission file number. The field allows up to 17 characters. The prefix may contain 1-3 digits, the sequence number may contain 1-8 digits, the optional suffix may contain 1-4 characters, and the fields are separated with a hyphen.

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No definition available.

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Indicate whether the registrant is one of the following: Large Accelerated Filer, Accelerated Filer, Non-accelerated Filer. Definitions of these categories are stated in Rule 12b-2 of the Exchange Act. This information should be based on the registrant's current or most recent filing containing the related disclosure.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Two-character EDGAR code representing the state or country of incorporation.

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Boolean flag that is true when the registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T during the preceding 12 months (or for such shorter period that the registrant was required to submit such files).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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The exact name of the entity filing the report as specified in its charter, which is required by forms filed with the SEC.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Boolean flag that is true when the registrant is a shell company as defined in Rule 12b-2 of the Exchange Act.

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- Definition

Indicates that the company is a Smaller Reporting Company (SRC).

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition

The Tax Identification Number (TIN), also known as an Employer Identification Number (EIN), is a unique 9-digit value assigned by the IRS.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Local phone number for entity.

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Title of a 12(b) registered security.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Name of the Exchange on which a security is registered.

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
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Trading symbol of an instrument as listed on an exchange.

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No definition available.

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Document and entity information.

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