CONSOLIDATED STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY - USD ($) shares in Thousands, $ in Thousands	Common Stock. Common Stock	Common Stock.	Additional paid-in capital	Retained earnings	Noncontrolling interest	Common Stock	Total
Balance at Dec. 31, 2015	$ 2		$ 172,354	$ 98,470	$ 791,524		$ 1,062,350
Balance (in shares) at Dec. 31, 2015	21,991
Changes in stockholders' equity
Net income				66,079	270,901		336,980
Stock and unit-based compensation			4,646		11,701		16,347
Stock and unit-based compensation (in shares)	111
Distributions					(15,216)		(15,216)
Issuance of Class A common stock in settlement of director fees			313				$ 313
Issuance of Class A common stock in settlement of director fees (in shares)	24
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.			6,877		(6,877)
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc. (in shares)	301						301
Tax effect of exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.			(1,418)				$ (1,418)
Balance at Dec. 31, 2016	$ 2		182,772	164,549	1,052,033		1,399,356
Balance (in shares) at Dec. 31, 2016	22,427
Changes in stockholders' equity
Net income							54,386
Balance at Mar. 31, 2017							1,457,595
Balance at Dec. 31, 2016	$ 2		182,772	164,549	1,052,033		1,399,356
Balance (in shares) at Dec. 31, 2016	22,427
Changes in stockholders' equity
Net income				100,757	210,765		311,522
Stock and unit-based compensation			7,545		14,406		21,951
Issuance of Class A common stock in settlement of director fees			160		178		338
Repurchase of common stock			(8,599)			$ (8,599)	$ (8,599)
Repurchase of common stock (in shares)	(505)					(505)
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.			27,119		(27,119)
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc. (in shares)	1,608						1,608
Tax effect of exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.			(4,894)				$ (4,894)
Balance at Dec. 31, 2017	$ 2		204,103	265,306	1,250,263		1,719,674
Balance (in shares) at Dec. 31, 2017	23,530
Balance at Mar. 31, 2017							1,457,595
Changes in stockholders' equity
Net income							50,746
Balance at Jun. 30, 2017							1,511,252
Changes in stockholders' equity
Net income							82,492
Balance at Sep. 30, 2017							1,590,291
Changes in stockholders' equity
Net income							123,898
Balance at Dec. 31, 2017	$ 2		204,103	265,306	1,250,263		1,719,674
Balance (in shares) at Dec. 31, 2017	23,530
Changes in stockholders' equity
Balance after adjustment (in shares)	23,530
Balance at Dec. 31, 2017	$ 2		204,103	265,306	1,250,263		1,719,674
Balance (in shares) at Dec. 31, 2017	23,530
Changes in stockholders' equity
Net income							66,926
Balance at Mar. 31, 2018							1,794,199
Balance at Dec. 31, 2017	$ 2		204,103	265,306	1,250,263		1,719,674
Balance (in shares) at Dec. 31, 2017	23,530
Changes in stockholders' equity
Net income				87,694	156,749		244,443
Stock and unit-based compensation			10,932		19,636		30,568
Stock and unit-based compensation (in shares)	299	23
Class A common stock dividends ($0.40 per share)				(10,054)			(10,054)
Issuance of Class A common stock in settlement of director fees			79		166		245
Repurchase of common stock			(467)			$ (5,293)	(467)
Repurchase of common stock (in shares)		(24)				(260)
Repurchase of Class A common stock			(1,554)		(3,272)		$ (4,826)
Repurchase of Class A common stock (in shares)	(236)
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc.	$ 1		33,155		(33,156)
Exchange of Class A units of Private National Mortgage Acceptance Company, LLC to Class A common stock of PennyMac Financial Services, Inc. (in shares)	1,635						1,635
Exchange of Class A common stock of subsidiary for common stock of PennyMac Financial Services, Inc. pursuant to a reorganization	$ (3)	$ 3
Exchange of Class A common stock of subsidiary for common stock of PennyMac Financial Services, Inc. pursuant to a reorganization (in shares)	(25,228)	25,228
Exchange of Class A unit of Private National Mortgage Acceptance Company, LLC for common stock of PennyMac Financial Services, Inc. pursuant to a reorganization, net of income tax effect		$ 5	1,064,315		(1,390,973)		$ (326,653)
Exchange of Class A unit of Private National Mortgage Acceptance Company, LLC for common stock of PennyMac Financial Services, Inc. pursuant to a reorganization, net of income tax effect (in shares)		52,263					52,263
Issuance of common stock in settlement of directors' fees			85				$ 85
Issuance of common stock in settlement of directors' fees (in shares)		4
Balance at Dec. 31, 2018		$ 8	1,310,648	343,135			1,653,791
Balance (in shares) at Dec. 31, 2018		77,494
Changes in stockholders' equity
Cumulative effect of change in accounting principle - Adoption of fair value accounting for all existing classes of mortgage servicing rights at fair value				189	587		776
Balance after adjustment	$ 2		204,103	265,495	$ 1,250,850		1,720,450
Balance at Mar. 31, 2018							1,794,199
Changes in stockholders' equity
Net income							68,405
Balance at Jun. 30, 2018							1,861,944
Changes in stockholders' equity
Net income							56,152
Balance at Sep. 30, 2018							1,916,710
Changes in stockholders' equity
Net income							52,960
Balance at Dec. 31, 2018		$ 8	$ 1,310,648	$ 343,135			$ 1,653,791
Balance (in shares) at Dec. 31, 2018		77,494