Investment Information (Other Than Temporary Impairments Recognized in Earnings) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	$ (724)	$ (1,951)	$ (2,970)	$ (2,974)
Fixed Maturities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(1,689)	(35)	(2,631)
Fixed Maturities | Mortgage backed securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(146)	(15)	(892)
Fixed Maturities | Corporate bonds
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(1,166)	0	(1,362)
Fixed Maturities | Non-US government securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(261)	0	(261)
Fixed Maturities | Asset backed securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(106)	(20)	(106)
Fixed Maturities | US government and government agencies
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(10)	0	(10)
Investment of funds received under securities lending arrangements
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	0	(6)	0	(87)
Equity securities
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Line Items]
Net impairment losses recognized in earnings	$ (724)	$ (256)	$ (2,935)	$ (256)