Significant Accounting Policies and Recently Issued Accounting Pronouncement - Income Taxes (Details)	12 Months Ended
Dec. 31, 2018
Income Taxes
Amount of tax benefits under the tax sharing agreement (as a percent)	85.00%

Percentage of tax benefits under the tax sharing agreement attributable to exchanged PennyMac unit holders.

No definition available.

Name:	pfsi_PercentageOfAmountOfTaxBenefits
Namespace Prefix:	pfsi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration