Investments (Details 3) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Other Than Temporary Impairment Credit Losses Recognized In Earnings Roll Forward
Balance, beginning of period	$ 63,947	$ 47,291
Initial impairments - credit loss OTTI recognized on securities not previously impaired	1,902	0
Additional impairments - credit loss OTTI recognized on securities previously impaired	8,720	658
Other Than Temporary Impairments Credit Losses On Securities Impaired To Fair Value	(11,381)	0
Credit loss impairments previously recognized on securities which were sold during the period	(952)	0
Balance, end of period	$ 62,236	$ 47,949