Summary of Investments (Net Realized Investment Gains and Losses and Proceeds) (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	$ 13,591	$ 1,297	$ 40,304	$ (6,567)
Debt Securities, Available-for-sale [Abstract]
Proceeds from sales	0	23,994	36,490	23,994
Gross realized gains	0	140	30	140
Gross realized losses	0	(307)	13	(307)
Fixed Maturities \| Available-for-sale
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	(8)	(219)	142	(193)
Fixed Maturities \| Change in fair value
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	501	(148)	2,247	(259)
Fixed Maturities \| Sales
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	92	349	92	905
Equity securities \| Change in fair value
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	12,499	305	37,133	(8,883)
Equity securities \| Sales
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	507	1,010	705	1,863
Mortgages
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	0	0	(15)	0
Discontinued Operations
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	0	0	0	(1,057)
Continuing and Discontinuing Operations
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses)	$ 13,591	$ 1,297	$ 40,304	$ (7,624)

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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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