Transactions with Affiliates - Correspondent Production (Details) - USD ($)		3 Months Ended		9 Months Ended
	Sep. 12, 2016	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
MBS Agreement
Transactions with Affiliates
Early purchase program facility fee per annum per early purchase facility	$ 1,500
Early purchase facility fee per loan	$ 35
The administrative fee plus accrued interest and sourcing fee percent	0.35%
Related party transaction, automatic renewal period	18 months
Fulfillment fee as a percent of UPB of all other mortgage loans, excluding Ginnie Mae mortgage loans	0.50%
MSR Recapture Agreement
Transactions with Affiliates
Related party transaction, automatic renewal period	18 months
Lending activity between the entity and affiliate
Minimum percent of total UPB of loans originated from refinancing of loans which a related party previously held the MSR required to be transferred	30.00%
PMT
Lending activity between the entity and affiliate
Fulfillment fee revenue		$ 26,256,000	$ 23,507,000	$ 52,759,000	$ 61,184,000
Proceeds from sale of mortgage loans held for sale to PennyMac Mortgage Investment Trust				2,336,162,000	373,108,000
PMT | MBS Agreement | Minimum
Transactions with Affiliates
The administrative fee plus accrued interest and sourcing fee percent	0.02%
PMT | MBS Agreement | Maximum
Transactions with Affiliates
The administrative fee plus accrued interest and sourcing fee percent	0.035%
PMT | Mortgage Lending
Lending activity between the entity and affiliate
Net gain on mortgage loans held for sale to PMT		19,722,000	11,396,000	49,396,000	12,280,000
Mortgage servicing rights and excess servicing spread recapture incurred		(1,157,000)	(1,495,000)	(3,518,000)	(4,696,000)
Total of gain on sale of loans and MSR recapture		18,565,000	9,901,000	45,878,000	7,584,000
Sale of mortgage loans held for sale to PMT		908,525,000	332,886,000	2,336,162,000	373,108,000
Fulfillment fee revenue		26,256,000	23,507,000	52,759,000	61,184,000
Unpaid principal balance of loans fulfilled for PennyMac Mortgage Investment Trust		7,517,883,000	6,530,036,000	17,139,884,000	17,079,969,000
Sourcing fees paid		2,689,000	3,275,000	8,221,000	9,340,000
Unpaid principal balance of loans purchased from PennyMac Mortgage Investment Trust		8,916,654,000	10,915,194,000	27,404,022,000	31,131,154,000
Tax service fee		$ 2,119,000	2,108,000	$ 4,869,000	5,377,000
Early purchase program fees earned from PMT			$ 1,000		$ 7,000