Transactions with Related Parties - Correspondent Production Activities - Additional Information (Detail)	6 Months Ended
	Jun. 30, 2019
Maximum [Member]
Mortgage Loans On Real Estate [Line Items]
Interest income and sourcing fee	0.035%
Minimum [Member]
Mortgage Loans On Real Estate [Line Items]
Interest income and sourcing fee	0.02%
PennyMac Loan Services, LLC [Member]
Mortgage Loans On Real Estate [Line Items]
Servicing agreement expiration date	Sep. 12, 2020
Renewal period of servicing agreement	18 months
PennyMac Loan Services, LLC [Member] | Fannie Mae Or Freddie Mac Mortgage Loans | Maximum [Member]
Mortgage Loans On Real Estate [Line Items]
Basis point for monthly fulfillment fee	0.35%
PennyMac Loan Services, LLC [Member] | Mortgage Loans Sold And Securitized | Maximum [Member]
Mortgage Loans On Real Estate [Line Items]
Basis point for monthly fulfillment fee	0.50%
Mortgage banking services [Member]
Mortgage Loans On Real Estate [Line Items]
Servicing agreement expiration date	Sep. 12, 2020
Renewal period of servicing agreement	18 months
Warehouse services [Member]
Mortgage Loans On Real Estate [Line Items]
Servicing agreement expiration date	Sep. 12, 2020
Renewal period of servicing agreement	18 months