CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($)	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Cash flow from operating activities
Net income	$ 1,003,490,000	$ 1,646,884,000	$ 392,965,000
Adjustments to reconcile net income to net cash used in operating activities:
Net gains on loans held for sale at fair value	(2,464,401,000)	(2,740,785,000)	(725,528,000)
Change in fair value of mortgage servicing rights, mortgage servicing liabilities and excess servicing spread	416,943,000	1,477,023,000	979,358,000
Mortgage servicing rights hedging gains	475,215,000	(918,180,000)	(395,497,000)
Capitalization of interest and advance on loans held for sale	(19,244,000)	(119,740,000)	(73,611,000)
Amortization of debt issuance cost (premiums), net	24,321,000	19,048,000	(4,100,000)
Results of real estate acquired in settlement of loans	(1,993,000)	(1,036,000)	(557,000)
Repricing of payable to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement		(280,000)	(379,000)
Stock based compensation expense	37,794,000	45,105,000	24,771,000
(Reversal of) provision for servicing advance losses	(47,878,000)	125,898,000	36,149,000
Impairment of capitalized software	728,000	13,145,000	0
Depreciation and amortization	28,645,000	25,575,000	15,021,000
Amortization of right-to-use assets	14,295,000	12,284,000	10,158,000
Origination of loans held for sale	(54,857,114,000)	(31,783,465,000)	(11,831,703,000)
Purchase of loans held for sale from non-affiliates	(4,896,527,000)	(3,799,336,000)	(1,725,227,000)
Purchase of loans from Ginnie Mae securities and early buyout investors	(23,644,025,000)	(11,156,684,000)	(6,271,447,000)
Sale to non-affiliates and principal payments of loans held for sale	154,450,942,000	102,840,312,000	61,214,102,000
Repurchase of loans subject to representations and warranties	(99,508,000)	(58,375,000)	(18,660,000)
Settlement of repurchase agreement derivatives		8,270,000	31,993,000
Increase in servicing advances	(232,574,000)	(391,440,000)	(98,121,000)
Sale of real estate acquired in settlement of loans	14,555,000	32,555,000	28,901,000
Decrease (increase) in other assets	61,871,000	(334,045,000)	(62,549,000)
Increase in accounts payable and accrued expenses	34,666,000	135,314,000	38,551,000
Decrease in operating lease liabilities	(16,310,000)	(13,421,000)	(12,680,000)
Net cash provided by (used in) operating activities	2,563,061,000	(6,198,938,000)	(2,245,123,000)
Cash flow from investing activities
Decrease in short-term investments	8,344,000	59,394,000	43,213,000
Net settlement of derivative financial instruments used for hedging of mortgage servicing rights	(434,397,000)	913,064,000	366,137,000
Purchase of mortgage servicing rights		(25,473,000)	(227,445,000)
Purchase of furniture, fixtures, equipment and leasehold improvements	(7,899,000)	(10,671,000)	(6,124,000)
Acquisition of capitalized software	(48,980,000)	(48,090,000)	(29,385,000)
Decrease (increase) in margin deposits	97,701,000	(131,840,000)	(21,127,000)
Net cash (used in) provided by investing activities	(304,369,000)	783,034,000	148,782,000
Cash flow from financing activities
Sale of assets under agreements to repurchase	136,179,744,000	102,232,005,000	63,803,260,000
Repurchase of assets sold under agreements to repurchase	(138,546,379,000)	(96,709,690,000)	(61,596,780,000)
Issuance of mortgage loan participation purchase and sale certificates	23,784,510,000	23,607,079,000	23,451,400,000
Repayment of mortgage loan participation purchase and sale certificates	(23,826,142,000)	(23,583,550,000)	(23,485,918,000)
Advances of obligations under capital lease			25,123,000
Repayments of obligations under capital lease	(8,375,000)	(8,946,000)	(10,918,000)
Issuance of unsecured senior notes	1,150,000,000	650,000,000
Payment of debt issuance costs	(37,567,000)	(30,112,000)	(6,603,000)
Issuance of common stock pursuant to exercise of stock options	7,536,000	9,389,000	5,145,000
Payment of withholding taxes relating to stock-based compensation	(8,993,000)	(5,265,000)	(4,634,000)
Payment of dividend to holders of common stock	(52,896,000)	(30,947,000)	(9,708,000)
Repurchase of common stock	(958,194,000)	(337,479,000)	(1,056,000)
Net cash (used in) provided by financing activities	(2,451,380,000)	5,760,107,000	2,128,995,000
Net (decrease) increase in cash and restricted cash	(192,688,000)	344,203,000	32,654,000
Cash and restricted cash at beginning of year	532,781,000	188,578,000	155,924,000
Cash and restricted cash at end of year	340,093,000	532,781,000	188,578,000
Cash	340,069,000	532,716,000	188,291,000
Restricted cash included in Other assets	24,000	65,000	287,000
PennyMac Mortgage Investment Trust
Adjustments to reconcile net income to net cash used in operating activities:
Accrual of interest on excess servicing spread financing payable to PennyMac Mortgage Investment Trust	1,280,000	8,418,000	10,291,000
Change in fair value of investment in common shares of PennyMac Mortgage Investment Trust	(195,000)	567,000	(275,000)
Purchase of loans held for sale from PennyMac Mortgage Investment Trust	(67,851,634,000)	(63,618,185,000)	(50,110,085,000)
Sale to Penny Mac Mortgage Investment Trust of loans held for sale		2,248,896,000	6,255,915,000
Decrease (increase) in receivable from affiliates	35,243,000	(48,320,000)	(20,257,000)
Increase (decrease) in payable to affiliate	36,549,000	37,642,000	(36,645,000)
Increase in income taxes payable	62,562,000	118,131,000	104,023,000
Cash flow from investing activities
Net change in assets purchased from PMT under agreement to resell	80,862,000	26,650,000	23,513,000
Cash flow from financing activities
Repayment of excess servicing spread financing	(134,624,000)	(32,377,000)	$ (40,316,000)
Exchanged Unit Holders
Adjustments to reconcile net income to net cash used in operating activities:
Payments to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement	$ (4,635,000)	$ (10,713,000)