Pending Acquisition of Delta National Bancorp (Details) $ / shares in Units, $ in Thousands	9 Months Ended
	Sep. 30, 2016 USD ($) Branch $ / shares shares	Dec. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Business Acquisition [Line Items]
Assets	$ 2,727,566	$ 2,615,345	$ 2,500,071
Delta National Bancorp [Member]
Business Acquisition [Line Items]
Assets	$ 112,000
Number of branches | Branch	4
Common stock issuable (in shares) | shares	12,074
Period for daily volume weighted average price	20 days
Common stock issuable	$ 6,600
Common stock value per share (in dollars per share) | $ / shares	$ 17.30
Cash to be paid per share to preferred shareholders (in dollars per share) | $ / shares	$ 19.827