Minimum Guarantees - Separate Account Liabilities for GMDB (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Net Amount at Risk by Product and Guarantee [Line Items]
Separate account liability	$ 469,176	$ 266,239
Net amount at risk, net of reinsurance	28,832	36,632
GMDB
Net Amount at Risk by Product and Guarantee [Line Items]
Separate account liability	55,607	55,999
Net amount at risk, net of reinsurance	$ 25,891	$ 29,050
Weighted average attained age	71 years	70 years
GLWB
Net Amount at Risk by Product and Guarantee [Line Items]
Separate account liability	$ 413,569	$ 210,240
Net amount at risk, net of reinsurance	$ 2,941	$ 7,582
Weighted average attained age	58 years	57 years