Fair Value - Financial Statement Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Assets:
Short-term investment at fair value	$ 12,194	$ 6,873
Loans held for sale	3,509,300	9,742,483
Derivative assets:
Derivative asset, before netting	157,995	398,672
Netting	(58,992)	(64,977)
Total derivative assets	99,003	333,695
Investment in PennyMac Mortgage Investment Trust	929	1,300
Derivative liabilities:
Derivative liability, before netting	83,246	54,702
Netting	(61,534)	(32,096)
Net amounts of liabilities presented in the consolidated balance sheet	21,712	22,606
Mortgage servicing liabilities	2,096	2,816
PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	929	1,300
Interest rate lock commitments
Derivative assets:
Total derivative assets	36,728	323,473
Recurring basis
Assets:
Short-term investment at fair value	12,194	6,873
Loans held for sale	3,509,300	9,742,483
Derivative assets:
Derivative asset, before netting	157,995	398,672
Netting	(58,992)	(64,977)
Total derivative assets	99,003	333,695
Mortgage servicing rights at fair value	5,953,621	3,878,078
Total assets	9,575,047	13,962,429
Derivative liabilities:
Derivative liability, before netting	83,246	54,702
Netting	(61,534)	(32,096)
Net amounts of liabilities presented in the consolidated balance sheet	21,712	22,606
Mortgage servicing liabilities	2,096	2,816
Total liabilities	23,808	25,422
Recurring basis | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	929	1,300
Recurring basis | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	36,728	323,473
Derivative liabilities:
Derivative liability, before netting	10,884	1,280
Recurring basis | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	2,433	20,485
Derivative liabilities:
Derivative liability, before netting	48,670	18,007
Recurring basis | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	80,754	40,215
Derivative liabilities:
Derivative liability, before netting	20,684	35,415
Recurring basis | MBS put options
Derivative assets:
Derivative asset, before netting	6,057	7,655
Recurring basis | Swaptions
Derivative assets:
Derivative asset, before netting		1,625
Recurring basis | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	2,820	2,078
Recurring basis | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	29,203	3,141
Recurring basis | Put options on Eurodollar futures | Sales
Derivative liabilities:
Derivative liability, before netting	3,008
Recurring basis | Level 1
Assets:
Short-term investment at fair value	12,194	6,873
Derivative assets:
Derivative asset, before netting	32,023	5,219
Total derivative assets	32,023	5,219
Total assets	45,146	13,392
Derivative liabilities:
Derivative liability, before netting	3,008
Net amounts of liabilities presented in the consolidated balance sheet	3,008
Total liabilities	3,008
Recurring basis | Level 1 | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	929	1,300
Recurring basis | Level 1 | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	2,820	2,078
Recurring basis | Level 1 | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	29,203	3,141
Recurring basis | Level 1 | Put options on Eurodollar futures | Sales
Derivative liabilities:
Derivative liability, before netting	3,008
Recurring basis | Level 2
Assets:
Loans held for sale	3,163,528	8,613,607
Derivative assets:
Derivative asset, before netting	89,244	69,980
Total derivative assets	89,244	69,980
Total assets	3,252,772	8,683,587
Derivative liabilities:
Derivative liability, before netting	69,354	53,422
Net amounts of liabilities presented in the consolidated balance sheet	69,354	53,422
Total liabilities	69,354	53,422
Recurring basis | Level 2 | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	2,433	20,485
Derivative liabilities:
Derivative liability, before netting	48,670	18,007
Recurring basis | Level 2 | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	80,754	40,215
Derivative liabilities:
Derivative liability, before netting	20,684	35,415
Recurring basis | Level 2 | MBS put options
Derivative assets:
Derivative asset, before netting	6,057	7,655
Recurring basis | Level 2 | Swaptions
Derivative assets:
Derivative asset, before netting		1,625
Recurring basis | Level 3
Assets:
Loans held for sale	345,772	1,128,876
Derivative assets:
Derivative asset, before netting	36,728	323,473
Total derivative assets	36,728	323,473
Mortgage servicing rights at fair value	5,953,621	3,878,078
Total assets	6,336,121	5,330,427
Derivative liabilities:
Derivative liability, before netting	10,884	1,280
Net amounts of liabilities presented in the consolidated balance sheet	10,884	1,280
Mortgage servicing liabilities	2,096	2,816
Total liabilities	12,980	4,096
Recurring basis | Level 3 | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	36,728	323,473
Derivative liabilities:
Derivative liability, before netting	$ 10,884	$ 1,280