Investment Securities (Narrative) (Details) $ in Thousands	6 Months Ended
	Jun. 30, 2015 USD ($) securities	Jun. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Investments [Abstract]
Pledged to secure deposits | $	$ 2,220,000		$ 2,120,000
Other-than-temporary impairment charges | $	$ 88	$ 88
Number of securities in a loss position for less than twelve months	37
Number of securities in a loss position for twelve months or longer	32