Investments (Narrative) (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) security	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) security	Jun. 30, 2016 USD ($)	Dec. 31, 2016 security
Gross gains on investments	$ 400	$ 600	$ 3,000	$ 700
Gross losses on investments	400	200	500	200
Proceeds from sale of investment securities	100	11,000	8,000	15,900
Other-than-temporary impairments	$ 3,407	$ 2,587	$ 3,407	$ 2,888
Equity Securities [Member]
Number of debt security positions, greater than 12 months | security	1		1		1
Debt Securities [Member]
Number of debt security positions, greater than 12 months | security	15		15		28