Label	Element	Value
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member]
Reclassification of Stranded Amounts in AOCI to Equity	pgr_ReclassificationofStrandedAmountsinAOCItoEquity	$ 4,300,000
Accounting Standards Update 2018-02 [Member] | AOCI Attributable to Parent [Member]
Reclassification of Stranded Amounts in AOCI to Equity	pgr_ReclassificationofStrandedAmountsinAOCItoEquity	(4,300,000)
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	1,300,200,000
Accounting Standards Update 2016-01 [Member] | AOCI Attributable to Parent [Member]
Cumulative Effect of New Accounting Principle in Period of Adoption	us-gaap_CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption	$ (1,300,200,000)