Derivative Instruments (Details 1) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2017	Mar. 31, 2016
Change in fair value of derivatives:
Net realized investment gains (losses)	[1]	$ 2,437	$ (218)
Change in fair value of embedded derivatives:
Net realized investment losses		$ (2,366)	$ (676)

[1] Includes the gains or losses recognized at the expiration of the option term or early termination and the changes in fair value for open options.