Document and Entity Information - shares	6 Months Ended
	Jun. 30, 2024	Jul. 31, 2024
Document And Entity Information [Line Items]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
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		86,860,960
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 2028
Trading Symbol	PMTU
Security Exchange Name	NYSE