Securities (Details Textual) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Schedule of Available-for-sale Securities [Line Items]
Gain on sale of investments	$ (9)	$ 0	$ (23)	$ 1
Gross unrealized losses	4,315		4,315			$ 8,189
Cumulative OTTI charges	13,995	$ 14,050	13,995	$ 14,050	$ 13,995	14,050	$ 14,079	$ 14,079
Amortized Cost	866,840		866,840			880,946
Securities available-for-sale	$ 885,836		$ 885,836			$ 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	44.9		44.9
Minimum [Member] | Moody Investor Service [Member]
Schedule of Available-for-sale Securities [Line Items]
Credit Quality Indicator Pricing	7.2		7.2
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	63.8		63.8
Maximum [Member] | Moody Investor Service [Member]
Schedule of Available-for-sale Securities [Line Items]
Credit Quality Indicator Pricing	16.3		16.3