Parent Company Information - Condensed Statements of Income (Details) - USD ($) $ 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
Revenue
Interest									$ 216,416	$ 143,179	$ 81,127
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
Interest									144,597	144,520	106,206
Total 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
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
Private National Mortgage Acceptance Company, LLC
Revenue
Revaluation of Payable to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement									1,126	32,940	551
PENNYMAC FINANCIAL SERVICES, INC. | Parent Company
Revenue
Dividends from subsidiaries									10,054		6,418
Interest											49
Revaluation of Payable to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement										32,940	551
Total net revenue									10,054	32,940	7,018
Expenses
Interest									32
Total expenses									32
Income before provision for income taxes									10,022	32,940	7,018
Provision for income taxes									20,897	24,387	46,103
Income before equity in undistributed earnings of subsidiaries									(10,875)	8,553	(39,085)
Equity in undistributed earnings of subsidiaries									98,569	92,204	105,164
Net income									$ 87,694	100,757	66,079
PENNYMAC FINANCIAL SERVICES, INC. | Parent Company | Private National Mortgage Acceptance Company, LLC
Revenue
Revaluation of Payable to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement										$ 32,940	$ 551