Net Gains on Mortgage Loans Held for Sale (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Cash (loss) gain:
Mortgage Loans	$ (107,414)	$ (40,747)	$ (399,457)	$ (98,408)
Hedging activities	(2,507)	(14,592)	89,322	(8,168)
Cash gain (loss), net of effects of cash hedging, on sale of mortgage loans held for sale	(109,921)	(55,339)	(310,135)	(106,576)
Non-cash gain:
Mortgage servicing rights and mortgage servicing liabilities resulting from mortgage loan sales, net	147,259	154,763	443,056	419,968
Provision for losses relating to representations and warranties on loans sold pursuant to mortgage loan sales	(1,842)	(1,596)	(4,550)	(4,294)
Provision for losses relating to representations and warranties on loans sold reduction in liability due to change in estimate	1,155	1,194	3,627	3,086
Change in fair value relating to mortgage loans and hedging derivatives held at quarter end:
Interest rate lock commitments	(18,526)	8,226	(21,109)	(5,008)
Mortgage loans	6,897	3,376	21,407	(2,554)
Hedging derivatives	13,327	(12,389)	11,100	(19,023)
From non-affiliates	38,349	98,235	143,396	285,599
Recapture payable to PennyMac Mortgage Investment Trust	18,565	9,901	45,878	7,584
Net gains on mortgage loans held for sale at fair value	$ 56,914	$ 108,136	$ 189,274	$ 293,183