Securities - (Details Textual)	3 Months Ended				9 Months Ended
	Sep. 30, 2015 USD ($)	Jun. 30, 2015 security	Sep. 30, 2014 USD ($)	Jun. 30, 2014 security	Sep. 30, 2015 USD ($) security institution	Sep. 30, 2014 USD ($)	Dec. 31, 2014 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 659,017,000		$ 724,000		$ 659,017,000	$ 724,000
Sale proceeds						1,099,000
Gross gains on sales of securities available for sale	0		375,000		96,000	375,000
Gain on sales of securities available for sale, net	0		$ 375,000		$ 96,000	$ 375,000
Number of securities, return to accrual status | security		1		1	1
Securities available for sale, at fair value	662,801,000				$ 662,801,000		$ 553,584,000
Number of securities representing interests in tranches of trusts (tranches) | security		3			3
Number of institutions issuing debt | institution					250
Secure government, public and trust deposits
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities pledged as collateral	721,834,000				$ 721,834,000		617,189,000
Short-term borrowings
Schedule of Available-for-sale Securities [Line Items]
Available for sale securities pledged as collateral	37,976,000				37,976,000		16,410,000
Trust preferred securities
Schedule of Available-for-sale Securities [Line Items]
Securities available for sale, at fair value	18,890,000				18,890,000		$ 19,756,000
Trust preferred securities | Pooled Trust Preferred Securities Xiii
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	1,117,000				1,117,000
Sale proceeds					1,213,000
Gross gains on sales of securities available for sale					96,000
Heritage Financial Group
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 7,231,000				7,231,000
Sale proceeds					7,231,000
Gain on sales of securities available for sale, net					$ 0