Realized and Unrealized Investment Gains and Losses (Change in Unrealized Gains (Losses) of Available For Sales Securities) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Realized and Unrealized Investment Gains Losses [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, No Previous Impairment	$ 33,300	$ 0	$ 6,000
Total change in unrealized gains (losses) before income taxes and noncontrolling interests	(192,186)	72,889	(399,122)
Income tax benefit (expense)	66,644	(23,223)	138,058
Noncontrolling interests	38	(33)	(28)
Total change in unrealized gains and losses	(125,504)	49,633	(261,092)
Debt Securities
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized gains (losses) before income taxes and noncontrolling interests	(144,445)	155,765	(401,812)
Debt Securities Previously Impaired
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized gains (losses) before income taxes and noncontrolling interests	(174)	865	1,076
Equity securities available for sale
Realized and Unrealized Investment Gains Losses [Line Items]
Other than Temporary Impairment, Credit Losses Recognized in Earnings, Additions, No Previous Impairment	24,300
Total change in unrealized gains (losses) before income taxes and noncontrolling interests	(27,809)	(69,016)	11,864
Investment funds
Realized and Unrealized Investment Gains Losses [Line Items]
Total change in unrealized gains (losses) before income taxes and noncontrolling interests	$ (19,758)	$ (14,725)	$ (10,250)