Investment Securities Summary of Gains and Losses from Equity and Debt Securities, and Losses from Other-than-Temporary Impairment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Gross Realized Gains	$ 2,586	$ 9,067	$ 2,393
Gross Realized Losses	(36)	(1)	(322)
Other- than- temporary Impairment Losses	0	0	(30)
Net Gains	2,550	9,066	2,041
Equity securities
Gross Realized Gains	2,005	6,496	335
Gross Realized Losses	(10)	(1)	0
Other- than- temporary Impairment Losses	0	0	(12)
Net Gains	1,995	6,495	323
Debt securities
Gross Realized Gains	581	2,571	2,058
Gross Realized Losses	(26)	0	(322)
Other- than- temporary Impairment Losses	0	0	(18)
Net Gains	$ 555	$ 2,571	$ 1,718