Variable Interest Entities (Details) (Juniperus Insurance Opportunity Fund Limited (Juniperus), USD $) In Millions	Jun. 30, 2011
Juniperus Insurance Opportunity Fund Limited (Juniperus)
Variable Interest Entity
Maximum potential loss on investment in Variable Interest Entities	$ 59

Quantifies the entity's maximum exposure to loss.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS140-4 and FIN46(R)-8
-Paragraph C6
-Subparagraph c

Name:	us-gaap_VariableInterestMaximumExposureToLoss
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant