Investments (Schedule Of Net Investment Income) (Details) (USD $) In Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010
Investment [Line Items]
Net investment income	$ 47,883	$ 59,479	$ 150,459	$ 193,975
Fixed Maturity Investments [Member]
Investment [Line Items]
Net investment income	47,877	55,165	149,471	193,815
Equity Securities And Other Invested Assets [Member]
Investment [Line Items]
Net investment income	3,397	6,438	10,608	7,684
Cash And Cash Equivalents [Member]
Investment [Line Items]
Net investment income	166	183	611	346
Expenses [Member]
Investment [Line Items]
Net investment income	$ (3,557)	$ (2,307)	$ (10,231)	$ (7,870)

The income earned from investments in securities and property, equipment and other capital assets. It includes rent from property and equipment, dividends from shares in corporations, and interest from bonds, loans, mortgages, derivatives, commercial paper, bank accounts, certificates of deposits, treasuries, and other financial securities. It does not include realized gains and losses on investments.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 16

-Article 12

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Paragraph 2

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 225

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-04.2)

-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Name:	us-gaap_NetInvestmentIncome
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration