Commitments and Contingencies - Commitments to Fund and Sell Mortgage Loans (Details) $ in Billions	Sep. 30, 2018 USD ($)
Commitments and Contingencies.
Total commitments to purchase and fund mortgage loans	$ 3.4

Amount to be expended to satisfy the terms of arrangements in which the entity has agreed to expend to purchase and fund mortgage loans.

No definition available.

Name:	pfsi_CommitmentsToPurchaseAndFundMortgageLoans
Namespace Prefix:	pfsi_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant