Discontinued Operations (Details)	Feb. 22, 2012
Discontinued Operations
Retained Share of AutoOne business (as a percent)	100.00%
Ceded share of AutoOne business (as a percent)	100.00%
AutoOne business
Discontinued Operations
Number of insurance companies sold	2

The percentage of the AutoOne business retained by the entity under the amendment of the pooling agreement.

No definition available.

Name:	ob_RetainedShareAutoOneBusinessWrittenPercentage
Namespace Prefix:	ob_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant