Segments (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segments and Related Information
Number of segments | segment			3
Revenues:
Net gains on loans held for sale at fair value	$ 682,173	$ 147,533	$ 1,026,455	$ 232,309
Loan origination fees	58,948	36,924	116,519	60,854
Fulfillment fees from PennyMac Mortgage Investment Trust			94,755	57,164
Net loan servicing fees	22,337	59,134	280,145	139,705
Net interest income (expense):
Interest income	47,318	70,900	119,882	129,233
Interest expense, before non-segment activities	53,207	52,924	114,719	90,467
Net interest expense, before non-segment activities	(5,889)	17,976	5,163	38,766
Management fees	8,288	8,832	17,343	16,080
Other	2,962	2,988	3,079	5,804
Total net revenues, before non-segment activities	821,634	302,977	1,543,459	550,682
Expenses	341,272	203,387	648,367	390,801
Income before provision for income taxes	480,362	99,590	895,092	159,881
Assets:
Segment assets at period end	23,226,475	8,398,376	23,226,475	8,398,376	$ 10,204,017
PMT
Revenues:
Fulfillment fees from PennyMac Mortgage Investment Trust	52,815	29,590	94,755	57,164
Net interest income (expense):
Management fees	8,288	8,832	$ 17,343	16,080
Mortgage banking
Segments and Related Information
Number of segments | segment			2
Operating segment
Assets:
Segment assets at period end	23,226,475	8,398,376	$ 23,226,475	8,398,376
Operating segment | Investment management
Net interest income (expense):
Interest expense, before non-segment activities	5	11	14	18
Net interest expense, before non-segment activities	(5)	(11)	(14)	(18)
Management fees	8,288	8,832	17,343	16,080
Other	2,250	1,539	3,057	3,102
Total net revenues, before non-segment activities	10,533	10,360	20,386	19,164
Expenses	5,822	6,341	11,918	13,023
Income before provision for income taxes	4,711	4,019	8,468	6,141
Assets:
Segment assets at period end	18,210	18,333	18,210	18,333
Operating segment | Mortgage banking
Revenues:
Net gains on loans held for sale at fair value	682,173	147,533	1,026,455	232,309
Loan origination fees	58,948	36,924	116,519	60,854
Fulfillment fees from PennyMac Mortgage Investment Trust			94,755	57,164
Net loan servicing fees	22,337	59,134	280,145	139,705
Net interest income (expense):
Interest income	47,318	70,900	119,882	129,233
Interest expense, before non-segment activities	53,202	52,913	114,705	90,449
Net interest expense, before non-segment activities	(5,884)	17,987	5,177	38,784
Other	712	1,449	22	2,702
Total net revenues, before non-segment activities	811,101	292,617	1,523,073	531,518
Expenses	335,450	197,046	636,449	377,778
Income before provision for income taxes	475,651	95,571	886,624	153,740
Assets:
Segment assets at period end	23,208,265	8,380,043	23,208,265	8,380,043
Operating segment | Mortgage banking | PMT
Revenues:
Fulfillment fees from PennyMac Mortgage Investment Trust	52,815	29,590
Operating segment | Mortgage banking Production
Revenues:
Net gains on loans held for sale at fair value	619,728	124,860	936,363	191,581
Loan origination fees	58,948	36,924	116,519	60,854
Fulfillment fees from PennyMac Mortgage Investment Trust			94,755	57,164
Net interest income (expense):
Interest income	19,205	18,900	45,790	33,269
Interest expense, before non-segment activities	12,642	13,898	32,799	17,813
Net interest expense, before non-segment activities	6,563	5,002	12,991	15,456
Other	361	117	351	605
Total net revenues, before non-segment activities	738,415	196,493	1,160,979	325,660
Expenses	200,352	98,249	382,785	180,410
Income before provision for income taxes	538,063	98,244	778,194	145,250
Assets:
Segment assets at period end	5,419,219	3,556,575	5,419,219	3,556,575
Operating segment | Mortgage banking Production | PMT
Revenues:
Fulfillment fees from PennyMac Mortgage Investment Trust	52,815	29,590
Operating segment | Mortgage banking Servicing
Revenues:
Net gains on loans held for sale at fair value	62,445	22,673	90,092	40,728
Net loan servicing fees	22,337	59,134	280,145	139,705
Net interest income (expense):
Interest income	28,113	52,000	74,092	95,964
Interest expense, before non-segment activities	40,560	39,015	81,906	72,636
Net interest expense, before non-segment activities	(12,447)	12,985	(7,814)	23,328
Other	351	1,332	(329)	2,097
Total net revenues, before non-segment activities	72,686	96,124	362,094	205,858
Expenses	135,098	98,797	253,664	197,368
Income before provision for income taxes	(62,412)	(2,673)	108,430	8,490
Assets:
Segment assets at period end	$ 17,789,046	$ 4,823,468	$ 17,789,046	$ 4,823,468