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Investments (Details 6) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Investments (Details 6) - USD ($) $ in Thousands	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Jan. 01, 2018
Other-than-temporary impairments on available-for-sale securities
Other-than-temporary impairments on available-for-sale securities recognized in earnings	$ 0	$ 0	$ (646)	$ (182)
Other-than-temporary impairments on available-for-sale securities recognized in other comprehensive income	0	$ 0	0	$ 0
Equity securities
Equity securities:
Total net realized losses	(1)		(189)
Less: net losses realized on securities sold	(52)		(86)
Net unrealized gains (losses) recognized during the period on securities held at reporting date	$ 51		$ (103)
Nonredeemable preferred stock \| Accounting Standards Update 2016-01 [Member]
Equity securities:
Cumulative effect adjustment due to ASU 2016-01					$ 100