Earnings Per Share of Common Stock (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Basic earnings per share of common stock:
Net income attributable to common stockholders	$ 14,489	$ 17,081	$ 48,945	$ 38,439
Weighted-average common stock outstanding	25,125	23,426	24,644	23,147
Basic earnings per share of common stock (in dollars per share)	$ 0.58	$ 0.73	$ 1.99	$ 1.66
Diluted earnings per share of common stock:
Net income attributable to common stockholders	$ 14,489	$ 17,081	$ 48,945	$ 38,439
Net income attributable to dilutive stock-based compensation units	552	888	2,435	1,816
Effect of net income attributable to noncontrolling interest, net of tax	29,580	37,996	101,921	86,473
Net income attributable to common stockholders for diluted earnings per share	$ 44,621	$ 55,965	$ 153,301	$ 126,728
Weighted-average common stock outstanding applicable to basic earnings per share	25,125	23,426	24,644	23,147
Effect of dilutive shares:
Common shares issuable under stock-based compensation plan	$ 1,476	$ 1,751	$ 1,818	$ 1,684
PennyMac Class A units exchangeable to common stock	52,312	53,239	52,492	53,400
Weighted-average shares of common stock outstanding applicable to diluted earnings per share	78,913	78,416	78,954	78,231
Diluted earnings per share of common stock (in dollars per share)	$ 0.57	$ 0.71	$ 1.94	$ 1.62
Total anti-dilutive stock-based compensation units	2,466	2,623	1,833	2,910
Performance-based RSUs
Effect of dilutive shares:
Total anti-dilutive stock-based compensation units	1,172		1,060	475
Stock Options
Effect of dilutive shares:
Total anti-dilutive stock-based compensation units	1,208	2,622	705	2,434
Weighted-average exercise price of anti-dilutive stock options	$ 17.79	$ 16.39	$ 17.79	$ 16.39
Time-based RSUs
Effect of dilutive shares:
Total anti-dilutive stock-based compensation units	86	1	68	1