Securities (Details Textual) - Asset Class [Domain] - Fair Value Hierarchy [Domain] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Gain on sale of investments	$ 10	$ (1)	$ 14	$ (1)
Gross unrealized losses	8,903		8,903			$ 8,189
Cumulative OTTI charges	13,995	$ 14,079	13,995	$ 14,079	$ 13,995	14,050	$ 14,079	$ 14,079
Amortized Cost	889,786		889,786			880,946
Securities available-for-sale	$ 901,550		$ 901,550			$ 897,053
Minimum [Member]
Schedule of Available-for-sale Securities [Line Items]
Basis point spread on variable rate	1.60%		1.60%
Minimum [Member] | Standard Poors [Member]
Schedule of Available-for-sale Securities [Line Items]
Credit Quality Indicator Pricing	4.4		4.4
Minimum [Member] | Moody Investor Service [Member]
Schedule of Available-for-sale Securities [Line Items]
Credit Quality Indicator Pricing	0.32		0.32
Maximum [Member]
Schedule of Available-for-sale Securities [Line Items]
Basis point spread on variable rate	1.80%		1.80%
Maximum [Member] | Standard Poors [Member]
Schedule of Available-for-sale Securities [Line Items]
Credit Quality Indicator Pricing	90.3		90.3
Maximum [Member] | Moody Investor Service [Member]
Schedule of Available-for-sale Securities [Line Items]
Credit Quality Indicator Pricing	90.5		90.5