Summary of Investments Narrative (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Schedule of Investments [Line Items]
Limited partnership and other corporation interests	$ 34,895,000	$ 40,980,000
Carrying value in relation to the activities of the VIEs	32,444,000	38,504,000
Maximum loss exposure of VIE	32,444,000	38,504,000
Fair value of securities on deposit with governmental authorities	7,659,000	14,000,000
Securities loaned to third parties at amortized cost	0	0
Total fixed maturity investments
Schedule of Investments [Line Items]
Change in net unrealized holding gain	$ (30,875,000)
Change in net realized holding gain (as a percent)	(9.00%)
Increase (decrease) in greater than twelve months unrealized losses and other-than-temporary impairment losses	$ 25,554,000
Unrealized loss and OTTI, 12 months or longer	$ 154,441,000	128,887,000
Corporate debt securities
Schedule of Investments [Line Items]
Unrealized losses and OTTI over twelve months on securities (as a percent)	90.00%
Unrealized loss and OTTI, 12 months or longer	$ 138,711,000	117,507,000
Perpetual debt securities
Schedule of Investments [Line Items]
Unrealized loss and OTTI, 12 months or longer	$ 6,791,000
Asset-backed securities
Schedule of Investments [Line Items]
Unrealized losses and OTTI over twelve months on securities (as a percent)	7.00%
Unrealized loss and OTTI, 12 months or longer	$ 11,417,000	$ 8,990,000
External Credit Rating, Non Investment Grade | Corporate debt securities
Schedule of Investments [Line Items]
Unrealized loss and OTTI, 12 months or longer	$ 13,285,000