Loans and Allowance for Credit Losses (Detail Textuals) - USD ($)	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015	Dec. 31, 2015
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining accretable fair value mark on loans	$ 8,300,000		$ 8,300,000		$ 7,030,000
Criteria amount for evaluation of impairment	500,000		500,000
Accruing substandard relationship	2,000,000		2,000,000
Gross additional interest income that would have been earned if the nonaccrual loans had performed as per original terms	262,000	$ 262,000	686,000	$ 686,000
Specific reserves	5,180,000		5,180,000		6,370,000
Loans outstanding classified as troubled debt restructurings	55,000		55,000		224,000
FHLB
Accounts, Notes, Loans and Financing Receivable [Line Items]
Pledged as collateral to secure FHLB advances	3,050,000,000		3,050,000,000		2,440,000,000
Indirect auto
Accounts, Notes, Loans and Financing Receivable [Line Items]
Remaining accretable fair value mark on loans	11,800,000		11,800,000		12,000,000
Loans Receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of purchased credit impaired loans	67,545,000		67,545,000		51,319,000
Unpaid principal balance of purchased credit impaired ("PCI") loans	95,300,000		95,300,000		71,000,000
Loans Receivable | Indirect auto
Accounts, Notes, Loans and Financing Receivable [Line Items]
Carrying value of purchased credit impaired loans	$ 8,000		$ 8,000		$ 49,000