SCHEDULE II - Condensed Financial Information Of Registrant Condensed Financial Information Of Registrant - Additional Information (Detail) - USD ($) $ in Billions	Dec. 31, 2018	Dec. 31, 2017
Significant Accounting Policies [Line Items]
Securities Held In Consolidated Non-Insurance Subsidiary	$ 2.9	$ 1.6
Parent Company
Significant Accounting Policies [Line Items]
Securities Held In Consolidated Non-Insurance Subsidiary	$ 2.9	$ 1.6

Securities held in the portfolio of a consolidated, non-insurance subsidiary of the holding company, net of any unsettled security transactions.

No definition available.

Name:	pgr_SecuritiesHeldInConsolidatedNonInsuranceSubsidiary
Namespace Prefix:	pgr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant