Earnings Per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands		3 Months Ended		9 Months Ended
	Nov. 01, 2018	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Basic earnings per share of common stock:
Net income attributable to common stockholders		$ 121,473	$ 14,489	$ 240,304	$ 48,945
Weighted-average common stock outstanding		78,361	25,125	78,119	24,644
Basic earnings per share of common stock (in dollars per share)		$ 1.55	$ 0.58	$ 3.08	$ 1.99
Diluted earnings per share of common stock:
Net income attributable to common stockholders		$ 121,473	$ 14,489	$ 240,304	$ 48,945
Net income attributable to dilutive stock-based compensation units			552		2,435
Effect of net income attributable to noncontrolling interest, net of tax			29,580		101,921
Net income attributable to common stockholders for diluted earnings per share		$ 121,473	$ 44,621	$ 240,304	$ 153,301
Weighted-average common stock outstanding applicable to basic earnings per share		78,361	25,125	78,119	24,644
Effect of dilutive shares:
Common shares issuable under stock-based compensation plan		$ 2,021	$ 1,476	$ 1,702	$ 1,818
PennyMac Class A units exchangeable to common stock			52,312		52,492
Weighted-average shares of common stock outstanding applicable to diluted earnings per share		80,382	78,913	79,821	78,954
Diluted earnings per share of common stock (in dollars per share)		$ 1.51	$ 0.57	$ 3.01	$ 1.94
Total anti-dilutive shares and units		1,723	2,466	1,873	1,833
Performance-based RSUs
Effect of dilutive shares:
Total anti-dilutive shares and units		1,157	1,172	985	1,060
Stock Options
Effect of dilutive shares:
Total anti-dilutive shares and units		566	1,208	888	705
Weighted-average exercise price of anti-dilutive stock options		$ 23.50	$ 17.79	$ 23.98	$ 17.79
Time-based RSUs
Effect of dilutive shares:
Total anti-dilutive shares and units			86		68
Class A Unit | New PFSI
Common stock conversion ratio (as a percent)	100.00%