Concentration of Third-party Mortgage Purchasers - Percent of Mortgage Loans Sold to Third-party Purchasers (Details) - Customer Concentration Risk - Mortgage Loans Sold	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
PennyMac Loan Services, LLC
Concentration Risk [Line Items]
Concentration risk percentage	37.00%	33.00%	41.00%
Fannie Mae
Concentration Risk [Line Items]
Concentration risk percentage	19.00%	24.00%	7.00%
Chase Manhattan Mortgage
Concentration Risk [Line Items]
Concentration risk percentage	13.00%	4.00%	8.00%
Ginnie Mae
Concentration Risk [Line Items]
Concentration risk percentage	9.00%	18.00%	4.00%
Wells Fargo Funding, Inc.
Concentration Risk [Line Items]
Concentration risk percentage	6.00%	9.00%	16.00%