Fair Value Measurements - Fair Value Measurements - Recurring basis Level 3 rollforward (Details) - Recurring basis - Level 3 - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Fixed maturities available-for-sale, Corporate debt securities
Recurring Level 3 financial assets and liabilities
Balance at the beginning of the period	$ 10,703	$ 15,056	$ 11,639	$ 4,538
Net income (loss)	0	0	0	0
Other comprehensive income (loss)	166	245	83	720
Settlements	(432)	(594)	(1,275)	(1,787)
Transfers out of Level 3	(357)		(367)
Transfers into Level 3				11,236
Balance at the end of the period	10,080	14,707	10,080	14,707
Total gains (losses) for the period included in net income attributable to the change in unrealized gains and losses relating to assets and liabilities	0	0	0	0
Embedded Derivative Financial Instruments
Recurring Level 3 financial assets and liabilities
Balance at the beginning of the period	9,595	30,687	5,712	11,257
Net income (loss)	(626)	(590)	(4,509)	(20,020)
Other comprehensive income (loss)	0	0	0	0
Settlements	0		0	0
Transfers out of Level 3	0		0
Transfers into Level 3				0
Balance at the end of the period	10,221	31,277	10,221	31,277
Total gains (losses) for the period included in net income attributable to the change in unrealized gains and losses relating to assets and liabilities	$ (626)	$ (590)	$ (4,509)	$ (20,020)