Fair Value - Financial Statement Items Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Short-term investment at fair value	$ 3,584	$ 12,194
Loans held for sale	6,772,423	3,509,300
Derivative assets:
Derivative asset, before netting	206,280	157,995
Netting	(95,616)	(58,992)
Total derivative assets	110,664	99,003
Investment in PennyMac Mortgage Investment Trust	925	929
Derivative liabilities:
Derivative liability, before netting	166,766	83,246
Netting	(117,679)	(61,534)
Net amounts of liabilities presented in the consolidated balance sheet	49,087	21,712
Mortgage servicing liabilities	2,011	2,096
Interest rate lock commitments
Derivative assets:
Total derivative assets	62,641	36,728
Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	78,507	2,433
Derivative liabilities:
Derivative liability, before netting	17,064	48,670
Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	19,232	80,754
Derivative liabilities:
Derivative liability, before netting	135,827	20,684
MBS put options
Derivative assets:
Derivative asset, before netting	6,604	6,057
MBS call options
Derivative assets:
Derivative asset, before netting	7,218
Derivative liabilities:
Derivative liability, before netting	7,830
Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	20,949	2,820
Call options on Eurodollar futures | Sales
Derivative liabilities:
Derivative liability, before netting	2,250
Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	11,129	29,203
Put options on Eurodollar futures | Sales
Derivative liabilities:
Derivative liability, before netting		3,008
Level 3
Assets:
Loans held for sale	312,789	345,772
Recurring basis
Assets:
Short-term investment at fair value	3,584	12,194
Loans held for sale	6,772,423	3,509,300
Derivative assets:
Derivative asset, before netting	206,280	157,995
Netting	(95,616)	(58,992)
Total derivative assets	110,664	99,003
Mortgage servicing rights at fair value	6,003,390	5,953,621
Total assets	12,890,986	9,575,047
Derivative liabilities:
Derivative liability, before netting	166,766	83,246
Netting	(117,679)	(61,534)
Net amounts of liabilities presented in the consolidated balance sheet	49,087	21,712
Mortgage servicing liabilities	2,011	2,096
Total liabilities	51,098	23,808
Recurring basis | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	925	929
Recurring basis | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	62,641	36,728
Derivative liabilities:
Derivative liability, before netting	3,795	10,884
Recurring basis | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	78,507	2,433
Derivative liabilities:
Derivative liability, before netting	17,064	48,670
Recurring basis | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	19,232	80,754
Derivative liabilities:
Derivative liability, before netting	135,827	20,684
Recurring basis | MBS put options
Derivative assets:
Derivative asset, before netting	6,604	6,057
Recurring basis | MBS call options
Derivative assets:
Derivative asset, before netting	7,218
Derivative liabilities:
Derivative liability, before netting	7,830
Recurring basis | Call options on Eurodollar futures
Derivative liabilities:
Derivative liability, before netting	2,250
Recurring basis | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	20,949	2,820
Recurring basis | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	11,129	29,203
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	3,584	12,194
Derivative assets:
Derivative asset, before netting	32,078	32,023
Total derivative assets	32,078	32,023
Total assets	36,587	45,146
Derivative liabilities:
Derivative liability, before netting	2,250	3,008
Net amounts of liabilities presented in the consolidated balance sheet	2,250	3,008
Total liabilities	2,250	3,008
Recurring basis | Level 1 | PennyMac Mortgage Investment Trust
Derivative assets:
Investment in PennyMac Mortgage Investment Trust	925	929
Recurring basis | Level 1 | Call options on Eurodollar futures
Derivative liabilities:
Derivative liability, before netting	2,250
Recurring basis | Level 1 | Call options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	20,949	2,820
Recurring basis | Level 1 | Put options on Eurodollar futures | Purchases
Derivative assets:
Derivative asset, before netting	11,129	29,203
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	6,459,634	3,163,528
Derivative assets:
Derivative asset, before netting	111,561	89,244
Total derivative assets	111,561	89,244
Total assets	6,571,195	3,252,772
Derivative liabilities:
Derivative liability, before netting	160,721	69,354
Net amounts of liabilities presented in the consolidated balance sheet	160,721	69,354
Total liabilities	160,721	69,354
Recurring basis | Level 2 | Forward contracts | Purchases
Derivative assets:
Derivative asset, before netting	78,507	2,433
Derivative liabilities:
Derivative liability, before netting	17,064	48,670
Recurring basis | Level 2 | Forward contracts | Sales
Derivative assets:
Derivative asset, before netting	19,232	80,754
Derivative liabilities:
Derivative liability, before netting	135,827	20,684
Recurring basis | Level 2 | MBS put options
Derivative assets:
Derivative asset, before netting	6,604	6,057
Recurring basis | Level 2 | MBS call options
Derivative assets:
Derivative asset, before netting	7,218
Derivative liabilities:
Derivative liability, before netting	7,830
Recurring basis | Level 3
Assets:
Loans held for sale	312,789	345,772
Derivative assets:
Derivative asset, before netting	62,641	36,728
Total derivative assets	62,641	36,728
Mortgage servicing rights at fair value	6,003,390	5,953,621
Total assets	6,378,820	6,336,121
Derivative liabilities:
Derivative liability, before netting	3,795	10,884
Net amounts of liabilities presented in the consolidated balance sheet	3,795	10,884
Mortgage servicing liabilities	2,011	2,096
Total liabilities	5,806	12,980
Recurring basis | Level 3 | Interest rate lock commitments
Derivative assets:
Derivative asset, before netting	62,641	36,728
Derivative liabilities:
Derivative liability, before netting	$ 3,795	$ 10,884