Other Comprehensive Income (Details 3) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Reclassifications out of accumulated other comprehensive income (loss)
Other realized investment (gains) losses, net	$ (31,806)	$ (18,650)
Net investment income	(331,785)	(358,856)
Prior service (benefits)	(151)	(181)
Actuarial (gains)	2,385	3,115
Tax expense or benefit	(7,860)	(10,653)
Net of tax	(13,144)	(17,877)
Amount reclassified from accumulated other comprehensive income (loss)
Reclassifications out of accumulated other comprehensive income (loss)
Net of tax	(13,144)	(17,877)
Unrealized holding (gains) losses, net, arising on fixed maturities, available-for-sale
Reclassifications out of accumulated other comprehensive income (loss)
Net of tax	(12,980)	(18,316)
Unrealized holding (gains) losses, net, arising on fixed maturities, available-for-sale | Amount reclassified from accumulated other comprehensive income (loss)
Reclassifications out of accumulated other comprehensive income (loss)
Other realized investment (gains) losses, net	(19,970)	(28,179)
Total before tax	(19,970)	(28,179)
Tax expense or benefit	(6,990)	(9,863)
Net of tax	(12,980)	(18,316)
Unrealized holding (gains) losses, net, arising on cash flow hedges
Reclassifications out of accumulated other comprehensive income (loss)
Net of tax	(1,616)	(1,468)
Unrealized holding (gains) losses, net, arising on cash flow hedges | Amount reclassified from accumulated other comprehensive income (loss)
Reclassifications out of accumulated other comprehensive income (loss)
Net investment income	(2,486)	(2,258)
Total before tax	(2,486)	(2,258)
Tax expense or benefit	(870)	(790)
Net of tax	(1,616)	(1,468)
Amortization of employee benefit plan items
Reclassifications out of accumulated other comprehensive income (loss)
Net of tax	1,452	1,907
Amortization of employee benefit plan items | Amount reclassified from accumulated other comprehensive income (loss)
Reclassifications out of accumulated other comprehensive income (loss)
Prior service (benefits)	(151)	(181)
Actuarial (gains)	2,385	3,115
Total before tax	2,234	2,934
Tax expense or benefit	782	1,027
Net of tax	$ 1,452	$ 1,907