Investments (Net Investment Income) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 285,625	$ 315,095	$ 385,302
Less: investment expenses	(7,974)	(9,085)	(8,193)
Net Investment Income, Total	277,651	306,010	377,109
Available For Sale Fixed Maturities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	246,479	282,108	349,906
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	7	278	932
Trading Account Assets [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	923	2,023	3,378
Commercial Mortgage Loans [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	28,449	28,044	26,665
Policy Loans [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	845	902	986
Short-term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	620	724	1,334
Other Long-term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 8,302	$ 1,016	$ 2,101