Selected Quarterly Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Revenue
Net gains on loans held for sale at fair value	$ 257,487	$ 235,732	$ 147,533	$ 84,776	$ 59,748	$ 56,914	$ 60,946	$ 71,414	$ 725,528	$ 249,022	$ 391,804
Loan origination fees	63,868	49,434	36,924	23,930	26,165	26,485	24,428	24,563	174,156	101,641	119,202
Net loan servicing fees	87,731	66,229	59,134	80,571	105,212	109,703	113,689	116,789	293,665	445,393	306,059
Other income	22,992	39,803	29,796	30,854	31,485	31,571	30,676	13,491
Total net revenue	490,375	436,347	302,977	247,705	251,201	250,929	244,298	238,201	1,477,404	984,629	955,463
Expenses	287,009	270,150	203,387	187,414	192,895	189,232	169,600	165,205	947,960	716,932	619,554
Income before provision for income taxes	203,366	166,197	99,590	60,291	58,306	61,697	74,698	72,996	529,444	267,697	335,909
Provision for income taxes	50,705	44,724	26,894	14,156	5,346	5,545	6,293	6,070	136,479	23,254	24,387
Net income	152,661	121,473	72,696	46,135	52,960	56,152	68,405	66,926	392,965	244,443	311,522
Less: Net income attributable to noncontrolling interest					14,211	41,663	50,568	50,307		156,749	210,765
Net income attributable to PennyMac Financial Services, Inc. common stockholders	$ 152,661	$ 121,473	$ 72,696	$ 46,135	$ 38,749	$ 14,489	$ 17,837	$ 16,619	$ 392,965	$ 87,694	$ 100,757
Earnings per share of Common Stock:
Basic (in dollars per share)	$ 1.95	$ 1.55	$ 0.93	$ 0.59	$ 0.65	$ 0.58	$ 0.71	$ 0.70	$ 5.02	$ 2.62	$ 4.34
Diluted (in dollars per share)	$ 1.88	$ 1.51	$ 0.92	$ 0.58	$ 0.63	$ 0.57	$ 0.70	$ 0.67	$ 4.89	$ 2.59	$ 4.03
Assets:
Loans held for sale	$ 4,912,953	$ 4,522,971	$ 3,506,406	$ 2,668,929	$ 2,521,647	$ 2,416,955	$ 2,527,231	$ 2,584,236	$ 4,912,953	$ 2,521,647
Mortgage servicing rights, at fair value	2,926,790	2,556,253	2,720,335	2,905,090	2,820,612	2,785,964	2,486,157	2,354,489	2,926,790	2,820,612
Servicing advances, net	331,169	271,501	271,534	284,230	313,197	259,609	258,900	284,145	331,169	313,197
Loans eligible for repurchase	1,046,527	892,631	1,007,435	1,094,702	1,102,840	889,335	879,621	1,018,488	1,046,527	1,102,840
Other assets	986,578	1,059,843	892,666	866,049	720,277	640,667	689,797	661,533	986,578	720,277
Total assets	10,204,017	9,303,199	8,398,376	7,819,000	7,478,573	6,992,530	6,841,706	6,902,891	10,204,017	7,478,573
Liabilities:
Short-term debt	4,639,001	4,053,514	3,270,261	2,449,908	2,332,143	2,222,385	2,264,041	2,336,826	4,639,001	2,332,143
Long-term debt	1,493,466	1,500,647	1,515,631	1,752,817	1,648,973	1,566,672	1,473,188	1,380,358	1,493,466	1,648,973
Liability for loans eligible for repurchase	1,046,527	892,631	1,007,435	1,094,702	1,102,840	889,335	879,621	1,018,488	1,046,527	1,102,840
Income taxes payable	504,569	480,559	441,336	414,636	400,546	74,158	67,357	58,956	504,569	400,546
Other liabilities	458,947	464,235	384,716	405,745	340,280	323,270	295,555	314,064	458,947	340,280
Total liabilities	8,142,510	7,391,586	6,619,379	6,117,808	5,824,782	5,075,820	4,979,762	5,108,692	8,142,510	5,824,782
Total equity	2,061,507	1,911,613	1,778,997	1,701,192	1,653,791	1,916,710	1,861,944	1,794,199	2,061,507	1,653,791	$ 1,719,674	$ 1,399,356
Total liabilities and stockholders' equity	10,204,017	9,303,199	8,398,376	7,819,000	7,478,573	6,992,530	6,841,706	6,902,891	10,204,017	7,478,573
PMT
Revenue
Fulfillment fees from affiliate	$ 58,297	$ 45,149	$ 29,590	$ 27,574	$ 28,591	$ 26,256	$ 14,559	$ 11,944	$ 160,610	$ 81,350	$ 80,359