Investment Securities - Debt Securities Credit Loss Recognized in Income, and Other Losses Recorded in Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Credit losses on debt securities held:
Balance, beginning of the period	$ 500	$ 11,355
Reductions for previous other-than-temporary losses realized on securities sold during the year	(500)	(10,855)
Balance, end of period	$ 0	$ 500