Condensed Consolidated Guarantor Financial Statements (Notes to Consolidated Guarantor Financial Statements) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Condensed Financial Statements, Captions [Line Items]
Subsidiary Investee Percentage Ownership	100.00%
Allied World Switzerland (Parent Guarantor)
Condensed Financial Statements, Captions [Line Items]
Cash Dividends Paid to Parent Company by Consolidated Subsidiaries	$ 294,000	$ 274,500	$ 355,000

This element represents disclosure of the aggregate cash dividends paid to the entity by consolidated subsidiaries.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 235

-Section S99

-Paragraph 2

-Subparagraph (SX 210.9-06)

-URI http://asc.fasb.org/extlink&oid=6882215&loc=d3e537971-122884

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 06

-Article 9

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph b

-Article 12

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 235

-SubTopic 10

-Section S99

-Paragraph 3

-Subparagraph (SX 210.12-04.(b))

-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24072-122690

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration