Investment Securities, Available-for-sale Securities, Gross Unrealized Loss Position (Details) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	$ 72,780	$ 78,389
12 months or more - Fair Value	294,662	491,378
Total - Fair Value	367,442	569,767
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	211	573
12 months or more - Gross Unrealized Loss	2,261	6,730
Total - Gross Unrealized Loss	2,472	7,303
U. S. Government Sponsored Enterprises [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	0	12,840
12 months or more - Fair Value	26,474	54,959
Total - Fair Value	26,474	67,799
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	0	81
12 months or more - Gross Unrealized Loss	46	541
Total - Gross Unrealized Loss	46	622
Mortgage Backed Securities and Collateralized Mortgage Obligations-Residential [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	65,185	65,549
12 months or more - Fair Value	176,976	325,476
Total - Fair Value	242,161	391,025
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	165	492
12 months or more - Gross Unrealized Loss	1,064	3,163
Total - Gross Unrealized Loss	1,229	3,655
Small Business Administration-Guaranteed Participation Securities [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	7,595	0
12 months or more - Fair Value	86,443	100,496
Total - Fair Value	94,038	100,496
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	46	0
12 months or more - Gross Unrealized Loss	1,149	2,777
Total - Gross Unrealized Loss	1,195	2,777
Mortgage Backed Securities and Collateralized Mortgage Obligations-Commercial [Member]
Available for sale securities unrealized loss position - Fair Value [Abstract]
Less than 12 months - Fair Value	0	0
12 months or more - Fair Value	4,769	10,447
Total - Fair Value	4,769	10,447
Available for sale securities unrealized loss position - Gross Unrealized Loss [Abstract]
Less than 12 months - Gross Unrealized Loss	0	0
12 months or more - Gross Unrealized Loss	2	249
Total - Gross Unrealized Loss	$ 2	$ 249