Investment Securities (Narrative) (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2015 USD ($) security	Dec. 31, 2014 USD ($) security
Investment Securities [Abstract]
Securities pledged as collateral	$ 781,700	$ 768,600
Securities transferred from available for sale to held to maturity (at fair value)	165,200	12,800
Unrealized holding losses included in accumulated other comprehensive income and in the carrying value of the held to maturity securities	$ 1,100	$ 51
Number of security positions, unrealized loss position | security	152	122
Number of security positions, unrealized loss position for more than 12 months | security	10	51
Fair value, continuous unrealized loss position for more than 12 months	$ 35,864	$ 207,942
Securities available for sale, 12 months or longer, Unrealized Losses	$ 513	$ 5,699
Number of security positions, unrealized loss position for less than 12 months | security	142	71
Securities, less than 12 months, Fair Value	$ 400,299	$ 69,888
Securities, less than 12 months, Unrealized Losses	$ 5,593	$ 236