Investments (Net Investment Income) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 35,448	$ 42,934	$ 74,437	$ 88,884
Less: investment expenses	(1,392)	(1,476)	(2,792)	(2,925)
Net investment income	34,056	41,458	71,645	85,959
Fixed maturities, available-for-sale
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	28,861	35,805	59,643	74,181
Trading account assets
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	29	21	31	30
Commercial mortgage and other loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	5,008	5,236	10,244	11,402
Policy loans
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	258	223	388	350
Short-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	57	72	101	130
Other long-term investments
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Gross investment income	$ 1,235	$ 1,577	$ 4,030	$ 2,791