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Investments (Details 6) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
Investments (Details 6) - USD ($) $ in Thousands	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 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	$ (646)	$ (61)	$ (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	(68)		(188)
Less: net losses realized on securities sold	0		(34)
Net unrealized losses recognized during the period on securities held at reporting date	$ (68)		$ (154)
Nonredeemable preferred stock \| Accounting Standards Update 2016-01 [Member]
Equity securities:
Cumulative effect adjustment due to ASU 2016-01					$ 100