Summary of Investments (Net Realized Investment Gains and Losses and Proceeds) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	$ 1,297	$ 1,081	$ (6,567)	$ 3,330
Debt Securities, Available-for-sale [Abstract]
Proceeds from sales	23,994		23,994
Proceeds from sales		0		1,096
Gross realized gains	140	0	140	1,046
Gross realized losses	(307)	0	(307)	0
Discontinued Operations
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	0	1,599	(1,057)	3,304
Debt Securities, Available-for-sale [Abstract]
Proceeds from sales	0		0
Proceeds from sales		0		3,963
Gross realized gains	0	0	0	1,254
Gross realized losses	0	0	0	(78)
Continuing and Discontinuing Operations
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	1,297	2,680	(7,624)	6,634
Fixed maturities \| Available-for-sale
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	(219)	103	(193)	527
Fixed maturities \| Change in fair value
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	(148)	176	(259)	547
Fixed maturities \| Sales
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	349	(11)	905	46
Equity securities
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	1,315	524	(7,020)	1,921
Real estate
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	$ 0	$ 289	$ 0	$ 289

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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