SOI Net investment income and Realized gains losses (Details 8) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net investment income
Investment income before expenses		$ 1,273,008	$ 1,248,381	$ 1,109,747
Investment expenses		(18,578)	(19,993)	(18,358)
Net investment income		1,254,430	1,228,388	1,091,389
Realized investment gains (losses):
Realized investment gains (losses)		83,710	147,371	(14,136)
Fixed maturity and short-term investments
Net investment income
Investment income before expenses		796,133	816,907	766,367
Realized investment gains (losses):
Realized investment gains (losses)		46,027	54,219	37,312
Mortgage loans on real estate
Net investment income
Investment income before expenses		150,284	149,497	147,944
Realized investment gains (losses):
Realized investment gains (losses)		31,841	6,857	10,895
Policy loans
Net investment income
Investment income before expenses		206,081	207,013	206,718
Limited partnership interests
Net investment income
Investment income before expenses		10,462	9,128	9,131
Net interest on funds withheld balances under reinsurance agreements, related party
Net investment income
Investment income before expenses		22,165	21,295	20,876
Derivative instruments
Net investment income
Investment income before expenses	[1]	78,655	39,533	(44,610)
Realized investment gains (losses):
Realized investment gains (losses)		5,840	90,504	(62,077)
Other
Net investment income
Investment income before expenses		9,228	5,008	3,321
Realized investment gains (losses):
Realized investment gains (losses)		$ 2	$ (4,209)	$ (266)

[1] Includes gains (losses) on the hedged asset for fair value hedges.