Noncontrolling Interest (Details) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Net income and the effects of changes in noncontrolling interest
Net income attributable to PennyMac Financial Services, Inc. common stockholders	$ 14,489	$ 17,081	$ 48,945	$ 38,439
Increase in the Company's additional paid-in capital for exchanges of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.	$ 4,377	$ 3,656	$ 32,501	$ 20,583
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc. (in shares)	131	251	1,616	1,297
Noncontrolling interest in Private National Mortgage Acceptance Company, LLC (as a percent)	67.50%		67.50%		69.20%
Class A Common Stock
Net income and the effects of changes in noncontrolling interest
Increase in the Company's additional paid-in capital for exchanges of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.			$ 1
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc. (in shares)	131	251	1,616	1,297