Parent Company Information - Condensed Statements of Cash Flows (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Cash flow from operating activities
Net income	$ 52,960	$ 56,152	$ 68,405	$ 66,926	$ 123,898	$ 82,492	$ 50,746	$ 54,386	$ 244,443	$ 311,522	$ 336,980
Decrease in deferred tax asset											18,668
Increase in income taxes payable									25,313	29,901	25,570
Net cash provided by (used in) operating activities									572,396	(883,412)	(938,325)
Cash flow from investing activities
Net cash used in investing activities									(322,611)	(339,231)	(34,739)
Cash flow from financing activities
Payment of dividend to Class A common stockholders											(7,631)
Repurchase of Class A common stock									(5,293)	(8,599)
Proceeds from Class A common stock options exercised									5,317	1,254	149
Net cash (used in) provided by financing activities									(132,034)	1,161,174	967,156
Net change in cash and restricted cash									117,751	(61,469)	(5,908)
Cash and restricted cash at beginning of year				38,173				99,642	38,173	99,642	105,550
Cash and restricted cash at end of year	$ 155,924				38,173				155,924	38,173	99,642
PENNYMAC FINANCIAL SERVICES, INC.
Cash flow from investing activities
Increase in investments in subsidiaries									(77)
Net cash used in investing activities									(77)
Cash flow from financing activities
Payment of dividend to Class A common stockholders									(10,054)
Repurchase of Class A common stock									(1,554)	(8,599)
PENNYMAC FINANCIAL SERVICES, INC. | Parent Company
Cash flow from operating activities
Net income									87,694	100,757	66,079
Equity in undistributed earnings of subsidiaries									(98,569)	(92,204)	(105,164)
Repricing of payable to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement										(32,940)	(551)
Decrease in deferred tax asset											18,668
Decrease (increase) in intercompany receivable									(3,737)	5,646	(76)
Payments to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement										(6,726)
Increase in income taxes payable									22,889	29,912	25,559
Net cash provided by (used in) operating activities									8,277	4,445	4,515
Cash flow from financing activities
Proceeds from Class A common stock options exercised									803	1,254	149
Net cash (used in) provided by financing activities									(10,805)	(7,345)	149
Net change in cash and restricted cash									(2,605)	(2,900)	4,664
Cash and restricted cash at beginning of year				$ 2,605				$ 5,505	$ 2,605	5,505	841
Cash and restricted cash at end of year					$ 2,605					$ 2,605	$ 5,505