v3.26.3
Fair Value - Summary of Changes in Fair Value Included in Current Period Results of Operations (Detail) - USD ($)
$ in Thousands
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Credit Risk Transfer Derivatives and Strips [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) $ 7,807 $ 10,800 $ 25,687 $ 24,226
Credit Risk Transfer Derivatives and Strips [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (7,807) 10,800 25,687 24,226
Credit Risk Transfer Derivatives and Strips [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Credit Risk Transfer Derivatives and Strips [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Credit Risk Transfer Derivatives and Strips [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Interest-only security payable [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (309) (5) 3,042 (2,336)
Interest-only security payable [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (309) (5) 3,042 (2,336)
Interest-only security payable [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Interest-only security payable [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Interest-only security payable [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Asset-backed financings of VIEs [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 506,513 (33,318) 612,513 (75,661)
Asset-backed financings of VIEs [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 526,604 (35,707) 629,492 (79,923)
Asset-backed financings of VIEs [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Asset-backed financings of VIEs [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (20,091) 2,389 (16,979) 4,262
Asset-backed financings of VIEs [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Liabilities, Total [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 506,204 (33,323) 615,555 (77,997)
Liabilities, Total [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (526,295) (35,712) 632,534 (82,259)
Liabilities, Total [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Liabilities, Total [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (20,091) 2,389 (16,979) 4,262
Liabilities, Total [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage Backed Securities [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (182,584) 58,109 (197,561) 155,180
Mortgage Backed Securities [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (166,947) 37,572 (199,928) 116,991
Mortgage Backed Securities [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage Backed Securities [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (15,637) 20,537 2,367 38,189
Mortgage Backed Securities [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for sale [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (96,355) 51,146 (67,472) 131,737
Loans held for sale [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for sale [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (96,355) 51,146 (67,472) 131,737
Loans held for sale [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for sale [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for investment [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (554,536) 37,240 (674,620) 75,405
Loans held for investment [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (531,924) 48,480 (626,215) 90,820
Loans held for investment [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Loans held for investment [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (22,612) (11,240) (48,405) (15,415)
Loans held for investment [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage servicing rights [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 125,403 (116,379) (17,360) (336,097)
Mortgage servicing rights [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage servicing rights [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage servicing rights [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 0 0 0 0
Mortgage servicing rights [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) 125,403 (116,379) (17,360) (336,097)
Assets, Total [Member]        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (700,265) 40,916 (931,326) 50,451
Assets, Total [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnInvestments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (691,064) 96,852 (800,456) 232,037
Assets, Total [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:GainLossOnSalesOfLoansNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (96,355) 51,146 (67,472) 131,737
Assets, Total [Member] | Location, Statement of Income, Balance [Axis]: us-gaap:InterestIncomeExpenseNet        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) (38,249) 9,297 (46,038) 22,774
Assets, Total [Member] | Location, Statement of Income, Balance [Axis]: pmt:ServicingIncomeLossNetOfValuationAdjustments        
Fair Value, Option, Quantitative Disclosures [Line Items]        
Changes in fair value included in current period income (expense) $ 125,403 $ (116,379) $ (17,360) $ (336,097)