Fair Value - Financial Statement Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2024	Dec. 31, 2023
Assets:
Short-term investment at fair value	$ 188,772	$ 10,268
Principal-only stripped mortgage-backed securities at fair value pledged to creditors	914,223
Loans held for sale	6,238,959	4,420,691
Derivative assets:
Derivative asset, before netting	212,056	258,809
Netting	(66,169)	(79,730)
Total derivative assets	145,887	179,079
Investment in PennyMac Mortgage Investment Trust	1,031	1,121
Derivative liabilities:
Derivative liability, before netting	76,956	101,866
Netting	(58,126)	(48,591)
Net amounts of liabilities presented in the consolidated balance sheet	18,830	53,275
Mortgage servicing liabilities	1,708	1,805
Interest rate lock commitments
Derivative assets:
Total derivative assets	72,682	90,313
Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	20,597	78,448
Derivative liabilities:
Derivative liability, before netting	51,481	5,141
Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	67,536	6,151
Derivative liabilities:
Derivative liability, before netting	21,545	92,796
MBS put options
Derivative assets:
Derivative asset, before netting	3,378	413
MBS call options
Derivative assets:
Derivative asset, before netting		6,265
Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	32,375	66,176
Derivative liabilities:
Derivative liability, before netting		3,209
Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	15,488	11,043
Principal-Only-Strip MBS
Assets:
Principal-only stripped mortgage-backed securities at fair value pledged to creditors	914,223
Recurring basis
Assets:
Short-term investment at fair value	188,772	10,268
Principal-only stripped mortgage-backed securities at fair value pledged to creditors	914,223
Loans held for sale	6,238,959	4,420,691
Derivative assets:
Derivative asset, before netting	212,056	258,809
Netting	(66,169)	(79,730)
Total derivative assets	145,887	179,079
Mortgage servicing rights	7,923,078	7,099,348
Total assets	15,411,950	11,710,507
Derivative liabilities:
Derivative liability, before netting	76,956	101,866
Netting	(58,126)	(48,591)
Net amounts of liabilities presented in the consolidated balance sheet	18,830	53,275
Mortgage servicing liabilities	1,708	1,805
Total liabilities	20,538	55,080
Recurring basis | Related Party | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	1,031	1,121
Recurring basis | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	72,682	90,313
Derivative liabilities:
Derivative liability, before netting	3,930	720
Recurring basis | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	20,597	78,448
Derivative liabilities:
Derivative liability, before netting	51,481	5,141
Recurring basis | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	67,536	6,151
Derivative liabilities:
Derivative liability, before netting	21,545	92,796
Recurring basis | MBS put options
Derivative assets:
Derivative asset, before netting	3,378	413
Recurring basis | MBS call options
Derivative assets:
Derivative asset, before netting		6,265
Recurring basis | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	32,375	66,176
Recurring basis | Call options on Eurodollar futures | Sales
Derivative liabilities:
Derivative liability, before netting		3,209
Recurring basis | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	15,488	11,043
Recurring basis | Level 1
Assets:
Short-term investment at fair value	188,772	10,268
Derivative assets:
Derivative asset, before netting	47,863	77,219
Total derivative assets	47,863	77,219
Total assets	237,666	88,608
Derivative liabilities:
Derivative liability, before netting		3,209
Net amounts of liabilities presented in the consolidated balance sheet		3,209
Total liabilities		3,209
Recurring basis | Level 1 | Related Party | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	1,031	1,121
Recurring basis | Level 1 | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	32,375	66,176
Recurring basis | Level 1 | Call options on Eurodollar futures | Sales
Derivative liabilities:
Derivative liability, before netting		3,209
Recurring basis | Level 1 | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	15,488	11,043
Recurring basis | Level 2
Assets:
Principal-only stripped mortgage-backed securities at fair value pledged to creditors	914,223
Loans held for sale	5,838,883	3,942,127
Derivative assets:
Derivative asset, before netting	91,511	91,277
Total derivative assets	91,511	91,277
Total assets	6,844,617	4,033,404
Derivative liabilities:
Derivative liability, before netting	73,026	97,937
Net amounts of liabilities presented in the consolidated balance sheet	73,026	97,937
Total liabilities	73,026	97,937
Recurring basis | Level 2 | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	20,597	78,448
Derivative liabilities:
Derivative liability, before netting	51,481	5,141
Recurring basis | Level 2 | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	67,536	6,151
Derivative liabilities:
Derivative liability, before netting	21,545	92,796
Recurring basis | Level 2 | MBS put options
Derivative assets:
Derivative asset, before netting	3,378	413
Recurring basis | Level 2 | MBS call options
Derivative assets:
Derivative asset, before netting		6,265
Recurring basis | Level 3
Assets:
Loans held for sale	400,076	478,564
Derivative assets:
Derivative asset, before netting	72,682	90,313
Total derivative assets	72,682	90,313
Mortgage servicing rights	7,923,078	7,099,348
Total assets	8,395,836	7,668,225
Derivative liabilities:
Derivative liability, before netting	3,930	720
Net amounts of liabilities presented in the consolidated balance sheet	3,930	720
Mortgage servicing liabilities	1,708	1,805
Total liabilities	5,638	2,525
Recurring basis | Level 3 | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	72,682	90,313
Derivative liabilities:
Derivative liability, before netting	$ 3,930	$ 720