Investment Securities (Debt Securities for which Credit Loss was Recognized in Income and Other Losses Recorded in Other Comprehensive Income) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Investment Securities [Abstract]
Credit losses on debt securities held, beginning of period	$ 109	$ 109	$ 1,205
Reductions related to actual losses incurred
Reductions for previous credit losses realized on securities sold during the year			(1,096)
Credit losses on debt securities held, end of period	$ 109	$ 109	$ 109