Employee Benefit Plans Assets Held in Deferral Plan Irrevocable Grantor Trust Account (Parenthetical) (Detail) (Progressive common shares) In Millions, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Progressive common shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Common shares held in Deferral Plan Irrevocable Grantor Trust account to be distributed in-kind	2.5	1.3

The maximum number of shares authorized for issuance under the deferred compensation arrangement as of the balance sheet date.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

Name:	us-gaap_DeferredCompensationArrangementWithIndividualSharesAuthorizedForIssuance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant