Transactions with Related Parties - Summary of Expenses (Detail) - PNMAC Capital Management LLC [Member] - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
		Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Related Party Transaction [Line Items]
Expenses incurred on the Company’s behalf, net		$ 6,318	$ 5,893	$ 15,511	$ 15,532
Common overhead incurred by PCM and its affiliates		1,867	1,489	5,811	5,450
Compensation		165	165	495	495
Total expenses incurred in transaction with affiliates		8,350	7,547	21,817	21,477
Payments and settlements during the periods	[1]	$ 31,752	$ 9,190	$ 91,100	$ 72,446

[1] Payments and settlements include payments and netting settlements made pursuant to master netting agreements between the Company and PFSI for the operating, investing and financing activities itemized in this Note.