Securities - Narrative (Details)	3 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) Security	Jun. 30, 2016 USD ($) Security	Jun. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Investments, Debt and Equity Securities [Abstract]
Proceeds from sales of securities		$ 72,800,000	$ 62,600,000
Gross gains realized on sale of securities		396,000	175,000
Gross loss realized on sale of securities		23,000	37,000
Tax expense related to realized gains		127,000	$ 47,000
Carrying value of securities pledged for fiduciary powers	$ 119,900,000	$ 119,900,000		$ 113,100,000
Number of securities temporarily impaired | Security	118	118
Number of securities temporarily impaired in investment grade | Security	113	113
Number of securities temporarily impaired in speculative grade | Security	5	5
Credit losses recognized in prior period earnings	$ 0	$ 0		0
Investment in FHLB stock	4,500,000	4,500,000		4,700,000
Federal Reserve Bank stock	$ 1,700,000	$ 1,700,000		$ 1,700,000