Transactions with Affiliates - Other Transactions, Reimbursement of Common Overhead Expenses (Details) - USD ($)			12 Months Ended
	Jul. 01, 2020	Sep. 12, 2016	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
PennyMac Mortgage Investment Trust
Transactions with Affiliates
Expense reimbursement amount, per quarter, relating to personnel		$ 120,000
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company			$ 24,378,000	$ 28,325,000	$ 10,182,000
Payments and settlements during the year			284,381,000	378,162,000	177,116,000
PennyMac Mortgage Investment Trust | Common overhead incurred
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company			4,906,000	5,172,000	5,340,000
PennyMac Mortgage Investment Trust | Compensation
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company			660,000	570,000	480,000
PennyMac Mortgage Investment Trust | Expenses incurred by related party (reporting entity), net
Reimbursement of common overhead and expenses incurred on behalf of affiliates
Reimbursement of common overhead and expenses incurred by the Company			$ 18,812,000	$ 22,583,000	$ 4,362,000
PCM
Transactions with Affiliates
Expense reimbursement amount, per quarter, relating to personnel	$ 165,000	$ 120,000
Related party transaction, renewal period	5 years