Net Interest Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Interest income:
Cash and short-term investments	$ 1,711	$ 1,933
Loans held for sale at fair value	46,426	31,343
Placement fees relating to custodial funds	23,209	23,261
Interest income, excluding related parties	71,346	56,537
Interest income	72,564	58,333
Interest expense:
Assets sold under agreements to repurchase	25,684	8,635
Mortgage loan participation purchase and sale agreements	1,810	2,311
Obligations under capital lease	167	66
Notes payable	15,349	17,995
Interest shortfall on repayments of mortgage loans serviced for Agency securitizations	14,871	4,311
Interest on mortgage loan impound deposits	1,657	1,159
Interest expense, non-affiliates	59,538	34,477
Interest expense	61,512	37,543
Net interest income	11,052	20,790
PMT
Interest income:
From PennyMac Mortgage Investment Trust	1,218	1,796
Interest expense:
To PennyMac Mortgage Investment Trust Excess servicing spread financing at fair value	1,974	3,066
Assets sold under agreements to repurchase
Interest expense:
Assets sold under agreements to repurchase	$ 25,684	8,635
Incentives recorded		$ 9,300