Non-controlling interests - Schedule of Noncontrolling Interest (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Noncontrolling Interest [Line Items]
Non-controlling interests	$ 55,014	$ 59,777
Catastrophe Fund and Catastrophe Reinsurer
Noncontrolling Interest [Line Items]
Non-controlling interests	48,161	19,646
Catastrophe Fund Manager
Noncontrolling Interest [Line Items]
Non-controlling interests	(162)	2
Joint Venture - Third Point Advisors LLC share
Noncontrolling Interest [Line Items]
Non-controlling Interests	$ 7,015	$ 40,129

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which is directly or indirectly attributable to that ownership interest in subsidiary equity which is not attributable to the parent (that is, noncontrolling interest, previously referred to as minority interest).

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.31)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 27

-Article 5

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 20

-Article 7

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant