Fair Value - Financial Statement Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Assets:
Short-term investment at fair value	$ 4,961	$ 6,873
Loans held for sale	3,586,810	9,742,483
Derivative assets:
Derivative asset, before netting	190,460	398,672
Netting	(86,559)	(64,977)
Total derivative assets	103,901	333,695
Investment in PennyMac Mortgage Investment Trust	1,037	1,300
Derivative liabilities:
Derivative liability, before netting	108,027	54,702
Netting	(65,325)	(32,096)
Net amounts of liabilities presented in the consolidated balance sheet	42,702	22,606
Mortgage servicing liabilities	2,337	2,816
Interest rate lock commitments
Derivative assets:
Total derivative assets	70,685	323,473
Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	61,855	20,485
Derivative liabilities:
Derivative liability, before netting	13,005	18,007
Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	24,499	40,215
Derivative liabilities:
Derivative liability, before netting	89,488	35,415
MBS put options
Derivative assets:
Derivative asset, before netting	7,868	7,655
Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	13,709	2,078
Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	11,844	3,141
Level 3
Assets:
Loans held for sale	503,553	1,128,876
Level 3 | Interest rate lock commitments
Assets:
Loans held for sale	65,151	322,193
Recurring basis
Assets:
Short-term investment at fair value	4,961	6,873
Loans held for sale	3,586,810	9,742,483
Derivative assets:
Derivative asset, before netting	190,460	398,672
Netting	(86,559)	(64,977)
Total derivative assets	103,901	333,695
Mortgage servicing rights at fair value	5,217,167	3,878,078
Total assets	8,913,876	13,962,429
Derivative liabilities:
Derivative liability, before netting	108,027	54,702
Netting	(65,325)	(32,096)
Net amounts of liabilities presented in the consolidated balance sheet	42,702	22,606
Mortgage servicing liabilities	2,337	2,816
Total liabilities	45,039	25,422
Recurring basis | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	1,037	1,300
Recurring basis | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	70,685	323,473
Derivative liabilities:
Derivative liability, before netting	5,534	1,280
Recurring basis | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	61,855	20,485
Derivative liabilities:
Derivative liability, before netting	13,005	18,007
Recurring basis | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	24,499	40,215
Derivative liabilities:
Derivative liability, before netting	89,488	35,415
Recurring basis | MBS put options
Derivative assets:
Derivative asset, before netting	7,868	7,655
Recurring basis | Swaptions | Purchases
Derivative assets:
Derivative asset, before netting		1,625
Recurring basis | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	13,709	2,078
Recurring basis | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	11,844	3,141
Recurring basis | Level 1
Assets:
Short-term investment at fair value	4,961	6,873
Derivative assets:
Derivative asset, before netting	25,553	5,219
Total derivative assets	25,553	5,219
Total assets	31,551	13,392
Recurring basis | Level 1 | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	1,037	1,300
Recurring basis | Level 1 | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	13,709	2,078
Recurring basis | Level 1 | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	11,844	3,141
Recurring basis | Level 2
Assets:
Loans held for sale	3,083,257	8,613,607
Derivative assets:
Derivative asset, before netting	94,222	69,980
Total derivative assets	94,222	69,980
Total assets	3,177,479	8,683,587
Derivative liabilities:
Derivative liability, before netting	102,493	53,422
Net amounts of liabilities presented in the consolidated balance sheet	102,493	53,422
Total liabilities	102,493	53,422
Recurring basis | Level 2 | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	61,855	20,485
Derivative liabilities:
Derivative liability, before netting	13,005	18,007
Recurring basis | Level 2 | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	24,499	40,215
Derivative liabilities:
Derivative liability, before netting	89,488	35,415
Recurring basis | Level 2 | MBS put options
Derivative assets:
Derivative asset, before netting	7,868	7,655
Recurring basis | Level 2 | Swaptions | Purchases
Derivative assets:
Derivative asset, before netting		1,625
Recurring basis | Level 3
Assets:
Loans held for sale	503,553	1,128,876
Derivative assets:
Derivative asset, before netting	70,685	323,473
Total derivative assets	70,685	323,473
Mortgage servicing rights at fair value	5,217,167	3,878,078
Total assets	5,791,405	5,330,427
Derivative liabilities:
Derivative liability, before netting	5,534	1,280
Net amounts of liabilities presented in the consolidated balance sheet	5,534	1,280
Mortgage servicing liabilities	2,337	2,816
Total liabilities	7,871	4,096
Recurring basis | Level 3 | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	70,685	323,473
Derivative liabilities:
Derivative liability, before netting	$ 5,534	$ 1,280