Commitments and Contingencies - Company's Outstanding Contractual Loan Commitments (Detail) $ in Thousands	Mar. 31, 2016 USD ($)
Commitments to purchase mortgage loans:
Mortgage loans acquired for sale at fair value	$ 1,234,894

Represents disclosure of amount of the company's contractual commitments to purchase recently originated mortgage loans.

No definition available.

Name:	pmt_MortgageLoansAcquiredForSaleAtFairValueOutstandingContractualLoanPurchaseCommitments
Namespace Prefix:	pmt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant