Summary of Investments Realized Investments Gaines (Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Schedule of Investments [Line Items]
Realized investments gains (losses), net	$ 92,882	$ 83,710	$ 147,371
Fixed maturity and short-term investments
Schedule of Investments [Line Items]
Realized investments gains (losses), net	87,108	46,027	54,219
Derivative instruments (1)
Schedule of Investments [Line Items]
Realized investments gains (losses), net	(5,318)	5,840	90,504
Mortgage loans on real estate
Schedule of Investments [Line Items]
Realized investments gains (losses), net	10,972	31,841	6,857
Other
Schedule of Investments [Line Items]
Realized investments gains (losses), net	$ 120	$ 2	$ (4,209)