Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ 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	Dec. 31, 2015
Revenue
Net mortgage loan servicing fees	$ 105,212	$ 109,703	$ 113,689	$ 116,789	$ 106,902	$ 78,081	$ 46,913	$ 74,163	$ 445,393	$ 306,059	$ 185,466
Net gains on mortgage loans held for sale at fair value	59,748	56,914	60,946	71,414	98,621	108,136	98,091	86,956	249,022	391,804	531,780
Mortgage loan origination fees	26,165	26,485	24,428	24,563	30,267	33,168	30,193	25,574	101,641	119,202	125,534
Fulfillment fees from affiliate											86,465
Other income	31,485	31,571	30,676	13,491	43,669	7,743	5,417	1,210
Total net revenue	251,201	250,929	244,298	238,201	298,634	250,635	201,721	204,473	984,629	955,463	931,887
Expenses	192,895	189,232	169,600	165,205	176,861	156,491	143,761	142,441	716,932	619,554	548,804
Income before provision for income taxes	58,306	61,697	74,698	72,996	121,773	94,144	57,960	62,032	267,697	335,909	383,083
(Benefit from) provision for income taxes	5,346	5,545	6,293	6,070	(2,125)	11,652	7,214	7,646	23,254	24,387	46,103
Net income	52,960	56,152	68,405	66,926	123,898	82,492	50,746	54,386	244,443	311,522	336,980
Less: Net income attributable to noncontrolling interest	14,211	41,663	50,568	50,307	61,580	65,411	40,267	43,507	156,749	210,765	270,901
Net income attributable to PennyMac Financial Services, Inc. common stockholders	$ 38,749	$ 14,489	$ 17,837	$ 16,619	$ 62,318	$ 17,081	$ 10,479	$ 10,879	$ 87,694	$ 100,757	$ 66,079
Earnings per share of Common Stock:
Basic (in dollars per share)	$ 0.65	$ 0.58	$ 0.71	$ 0.70	$ 2.67	$ 0.73	$ 0.45	$ 0.48	$ 2.62	$ 4.34	$ 2.98
Diluted (in dollars per share)	$ 0.63	$ 0.57	$ 0.70	$ 0.67	$ 2.44	$ 0.71	$ 0.44	$ 0.47	$ 2.59	$ 4.03	$ 2.94
Assets:
Mortgage loans held for sale	$ 2,521,647	$ 2,416,955	$ 2,527,231	$ 2,584,236	$ 3,099,103	$ 2,935,593	$ 3,037,602	$ 2,277,751	$ 2,521,647	$ 3,099,103
Mortgage servicing rights	2,820,612	2,785,964	2,486,157	2,354,489	2,119,588	2,016,485	1,951,599	1,725,061	2,820,612	2,119,588
Servicing advances, net	313,197	259,609	258,900	284,145	318,066	262,650	291,907	317,513	313,197	318,066
Mortgage loans eligible for repurchase	1,102,840	889,335	879,621	1,018,488	1,208,195	584,394	462,487	318,378	1,102,840	1,208,195
Other assets	720,277	640,667	689,797	661,533	623,141	589,247	661,143	612,674	720,277	623,141
Total assets	7,478,573	6,992,530	6,841,706	6,902,891	7,368,093	6,388,369	6,404,738	5,251,377	7,478,573	7,368,093
Liabilities:
Short-term debt	2,332,143	2,222,385	2,264,041	2,336,826	2,922,542	2,640,743	3,311,029	2,331,357	2,332,143	2,922,542
Long-term debt	1,648,973	1,566,672	1,473,188	1,380,358	1,135,401	1,151,545	671,789	690,476	1,648,973	1,135,401
Liability for mortgage loans eligible for repurchase	1,102,840	889,335	879,621	1,018,488	1,208,195	584,394	462,487	318,378	1,102,840	1,208,195
Other liabilities	740,826	397,428	362,912	373,020	382,281	421,396	448,181	453,571	740,826	382,281
Total liabilities	5,824,782	5,075,820	4,979,762	5,108,692	5,648,419	4,798,078	4,893,486	3,793,782	5,824,782	5,648,419
Total equity	1,653,791	1,916,710	1,861,944	1,794,199	1,719,674	1,590,291	1,511,252	1,457,595	1,653,791	1,719,674	$ 1,399,356	$ 1,062,350
Total liabilities and stockholders' equity	7,478,573	6,992,530	6,841,706	6,902,891	7,368,093	6,388,369	6,404,738	5,251,377	7,478,573	7,368,093
PMT
Revenue
Net mortgage loan servicing fees											185,466
Fulfillment fees from affiliate	$ 28,591	$ 26,256	$ 14,559	$ 11,944	$ 19,175	$ 23,507	$ 21,107	$ 16,570	$ 81,350	$ 80,359	$ 86,465