Summary of Investments (Net Realized Investment Gains and Losses and Proceeds) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	$ 67	$ 2,129	$ 3,397	$ 4,832
Available-for-sale Securities [Abstract]
Proceeds from sales	2,293	0	3,388	1,968
Gross realized gains	0	0	1,046	921
Gross realized losses	0	0	0	0
Discontinued Operations
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	296	461	3,600	1,409
Available-for-sale Securities [Abstract]
Proceeds from sales	1,844	2,007	5,807	3,081
Gross realized gains	0	11	1,254	65
Gross realized losses	0	0	(78)	0
Continuing and Discontinuing Operations
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	363	2,590	6,997	6,241
Fixed maturities: | Available-for-sale
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	118	484	645	898
Fixed maturities: | Change in fair value
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	(43)	148	504	519
Fixed maturities: | Sales
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	72	107	117	568
Equity securities: | Available-for-sale
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	3	1,375	1,553	2,359
Equity securities: | Change in fair value
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	(124)	(5)	232	325
Equity securities: | Sales
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	41	20	57	(6)
Cash equivalents
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	0	0	0	169
Real estate
Gain (Loss) on Investments [Line Items]
Net realized investment gains (losses)	$ 0	$ 0	$ 289	$ 0