Related Party Transactions - Financing Activities (Details) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019	Feb. 01, 2013
Financing activities:
Issuance pursuant to recapture agreement			$ 1,393,000	$ 1,327,000
Repayments			25,112,000	30,901,000
PMT
Financing activities:
Interest expense	$ 2,070,000	$ 2,291,000	6,416,000	8,124,000
Change in fair value	3,135,000	3,864,000	18,293,000	11,519,000
Excess servicing spread financing at fair value payable to affiliate	142,990,000		142,990,000		$ 178,586,000
PMT | 2/1/13 Spread Acquisition Agreement
Financing activities:
Maximum ESS recapture obligation						$ 200,000
Excess servicing spread financing | PMT
Financing activities:
Balance at the beginning of the period	151,206,000	194,156,000	178,586,000	216,110,000
Issuance pursuant to recapture agreement	531,000	377,000	1,393,000	1,327,000
Interest expense	2,070,000	2,291,000	6,416,000	8,124,000
Repayments	(7,682,000)	(9,819,000)	(25,112,000)	(30,901,000)
Change in fair value	(3,135,000)	(3,864,000)	(18,293,000)	(11,519,000)
Balance at the end of the period	142,990,000	183,141,000	142,990,000	183,141,000
Excess servicing spread recapture recognized	$ 525,000	$ 429,000	$ 1,441,000	$ 1,311,000