Segments (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) segment	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Segments and Related Information
Number of segments | segment	3
Revenues:
Net mortgage loan servicing fees	$ 80,571	$ 116,789
Net gains on mortgage loans held for sale at fair value	84,776	71,414
Mortgage loan origination fees	23,930	24,563
Net interest income (expense):
Interest income	58,333	42,615
Interest expense, before non-segment activities	37,543	36,745
Net interest expense, before non-segment activities	20,790	5,870
Management fees	7,248	5,775
Other	2,816	2,026
Total net revenues, before non-segment activities	247,705	238,201
Expenses	187,414	165,205
Income before provision for income taxes	60,291	72,996
Assets:
Segment assets at year end	7,819,000		$ 7,478,573
PMT
Revenues:
Fulfillment fees from PennyMac Mortgage Investment Trust	27,574	11,944
Net interest income (expense):
Management fees	7,248	5,696
Assets:
Receivable	$ 29,951		$ 33,464
Investment Funds
Net interest income (expense):
Management fees		79
Carried Interest from Investment Funds		(180)
Mortgage banking
Segments and Related Information
Number of segments | segment	2
Operating segment
Assets:
Segment assets at year end	$ 7,819,000	6,894,177
Working capital		8,700
Operating segment | Investment management
Net interest income (expense):
Interest expense, before non-segment activities	7	16
Net interest expense, before non-segment activities	(7)	(16)
Management fees	7,248	5,775
Other	1,563	1,315
Total net revenues, before non-segment activities	8,804	6,894
Expenses	6,682	5,943
Income before provision for income taxes	2,122	951
Assets:
Segment assets at year end	17,719	11,877
Operating segment | Investment management | Investment Funds
Net interest income (expense):
Carried Interest from Investment Funds		(180)
Operating segment | Mortgage banking
Revenues:
Net mortgage loan servicing fees	80,571	116,789
Net gains on mortgage loans held for sale at fair value	84,776	71,414
Mortgage loan origination fees	23,930	24,563
Net interest income (expense):
Interest income	58,333	42,615
Interest expense, before non-segment activities	37,536	36,729
Net interest expense, before non-segment activities	20,797	5,886
Other	1,253	711
Total net revenues, before non-segment activities	238,901	231,307
Expenses	180,732	159,262
Income before provision for income taxes	58,169	72,045
Assets:
Segment assets at year end	7,801,281	6,882,300
Operating segment | Mortgage banking | PMT
Revenues:
Fulfillment fees from PennyMac Mortgage Investment Trust	27,574	11,944
Operating segment | Mortgage banking Production
Revenues:
Net gains on mortgage loans held for sale at fair value	66,721	36,198
Mortgage loan origination fees	23,930	24,563
Net interest income (expense):
Interest income	14,369	14,248
Interest expense, before non-segment activities	3,915	2,102
Net interest expense, before non-segment activities	10,454	12,146
Other	488	316
Total net revenues, before non-segment activities	129,167	85,167
Expenses	82,161	67,997
Income before provision for income taxes	47,006	17,170
Assets:
Segment assets at year end	2,501,468	2,251,354
Operating segment | Mortgage banking Production | PMT
Revenues:
Fulfillment fees from PennyMac Mortgage Investment Trust	27,574	11,944
Operating segment | Mortgage banking Servicing
Revenues:
Net mortgage loan servicing fees	80,571	116,789
Net gains on mortgage loans held for sale at fair value	18,055	35,216
Net interest income (expense):
Interest income	43,964	28,367
Interest expense, before non-segment activities	33,621	34,627
Net interest expense, before non-segment activities	10,343	(6,260)
Other	765	395
Total net revenues, before non-segment activities	109,734	146,140
Expenses	98,571	91,265
Income before provision for income taxes	11,163	54,875
Assets:
Segment assets at year end	$ 5,299,813	$ 4,630,946