Related Party Transactions - Exchanged Private National Mortgage Acceptance Company, LLC Unitholders (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Dec. 31, 2019
Transactions with Affiliates
Amount of tax benefits under the tax sharing agreement (as a percent)	85.00%
Payments to exchanged Private National Mortgage Acceptance Company, LLC unitholders under tax receivable agreement	$ (10,374)
Payable to exchanged PNMAC unitholders under tax receivable agreement	35,800		$ 46,200
Private National Mortgage Acceptance Company, LLC
Transactions with Affiliates
Payment of tax liability under the tax receivable agreement to Private National Mortgage Acceptance Company, LLC unitholders	$ 10,400	$ 0