Transactions with Affiliates - Correspondent Production (Details) - USD ($)		3 Months Ended								12 Months Ended
	Sep. 12, 2016	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Lending activity between the entity and affiliate
Fulfillment fee revenue												$ 86,465,000
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
Total of gain on sale of loans and MSR recapture										$ 64,583,000	$ 21,989,000	(8,092,000)
Sale of mortgage loans held for sale to PMT										3,343,028,000	904,097,000	21,541,000
Fulfillment fee revenue		$ 28,591,000	$ 26,256,000	$ 14,559,000	$ 11,944,000	$ 19,175,000	$ 23,507,000	$ 21,107,000	$ 16,570,000	81,350,000	80,359,000	86,465,000
Proceeds from sale of mortgage loans held for sale to PennyMac Mortgage Investment Trust										3,343,028,000	904,097,000	21,541,000
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 (loss) on mortgage loans held for sale to PMT										69,359,000	28,238,000
Mortgage servicing rights and excess servicing spread recapture incurred										(4,776,000)	(6,249,000)	(8,092,000)
Total of gain on sale of loans and MSR recapture										64,583,000	21,989,000	(8,092,000)
Sale of mortgage loans held for sale to PMT										3,343,028,000	904,097,000	21,541,000
Fulfillment fee revenue										81,350,000	80,359,000	86,465,000
Unpaid principal balance of mortgage loans fulfilled for PMT										26,194,303,000	22,971,119,000	23,188,386,000
Sourcing fees paid										10,925,000	12,084,000	11,976,000
Unpaid principal balance of mortgage loans purchased from PMT										36,415,933,000	40,561,241,000	39,908,163,000
Proceeds from sale of mortgage loans held for sale to PennyMac Mortgage Investment Trust										3,343,028,000	904,097,000	21,541,000
Tax service fee										$ 7,433,000	7,078,000	6,690,000
Early purchase program fees earned from PMT											$ 7,000	$ 30,000