Agreement and Plan of Reorganization and Merger - Additional Information (Detail) $ / shares in Units, $ in Millions	6 Months Ended
	Jun. 30, 2015 $ / shares	Jun. 26, 2015 USD ($) $ / shares	Dec. 31, 2014 $ / shares
Business Acquisition [Line Items]
Common stock stated value per share	$ 1.00		$ 1.00
First Merchants [Member]
Business Acquisition [Line Items]
Merger Agreement date	Jun. 25, 2015
Closing price of common stock, per share		$ 25.13
Estimated transaction value of merger | $		$ 68.8
Share of outstanding common stock, per share		$ 1.00
Common stock exchange ratio		0.9037
Common stock stated value per share		$ 0.125