Net Interest Income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Interest income:
Cash and short-term investments	$ 1,933	$ 608
Mortgage loans held for sale at fair value	31,343	26,607
Placement fees relating to custodial funds	23,261	13,424
Interest income, excluding related parties	56,537	40,639
Interest income	58,333	42,615
Interest expense:
Assets sold under agreements to repurchase	8,635	6,732
Mortgage loan participation purchase and sale agreements	2,311	1,727
Notes payable	17,995	18,222
Obligations under capital lease	66	170
Interest shortfall on repayments of mortgage loans serviced for Agency securitizations	4,311	4,830
Interest on mortgage loan impound deposits	1,159	1,130
Interest expense, non-affiliates	34,477	32,811
Interest expense	37,543	36,745
Net interest income	20,790	5,870
PMT
Interest income:
From PennyMac Mortgage Investment Trust	1,796	1,976
Interest expense:
To PennyMac Mortgage Investment Trust Excess servicing spread financing at fair value	3,066	3,934
Assets sold under agreements to repurchase
Interest expense:
Assets sold under agreements to repurchase	8,635	6,732
Incentives recorded	$ 9,300	$ 10,200