Net Gains on Mortgage Loans Held for Sale (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	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
Cash (loss) gain:
Mortgage Loans									$ (469,647)	$ (174,669)	$ (62,283)
Hedging activities									93,288	(16,866)	10,275
Cash gain (loss), net of effects of cash hedging, on sale of mortgage loans held for sale									(376,359)	(191,535)	(52,008)
Non-cash gain:
Mortgage servicing rights and mortgage servicing liabilities resulting from mortgage loan sales									584,156	563,872	562,540
Provision for losses relating to representations and warranties on loans sold pursuant to mortgage loan sales									(5,824)	(5,890)	(7,090)
Provision for losses relating to representations and warranties on loans sold reduction in liability due to change in estimate									4,672	4,301	7,672
Change in fair value relating to mortgage loans and derivatives held at year end:
Interest rate lock commitments									(8,934)	(1,120)	15,618
Mortgage loans									(1,506)	4,576	2,796
Hedging derivatives									(11,766)	(4,389)	10,344
From non-affiliates									184,439	369,815	539,872
Net gains on mortgage loans held for sale at fair value	$ 59,748	$ 56,914	$ 60,946	$ 71,414	$ 98,621	$ 108,136	$ 98,091	$ 86,956	249,022	391,804	531,780
PMT
Change in fair value relating to mortgage loans and derivatives held at year end:
Recapture payable to PennyMac Mortgage Investment Trust									$ 64,583	$ 21,989	$ (8,092)