Acquisition and Divestiture Activity - Schedule of Components of Estimated Fair Value of Intangible Assets (Detail) (Tower Financial Corporation [Member], USD $) In Millions, unless otherwise specified	6 Months Ended
	Jun. 30, 2014
Business Acquisition [Line Items]
Estimated Fair Value	$ 8.4
Core deposit intangible [Member]
Business Acquisition [Line Items]
Estimated Fair Value	4.6
Estimated Useful Lives (Years)	7 years
Trust customer relationship intangible [Member]
Business Acquisition [Line Items]
Estimated Fair Value	$ 3.8
Estimated Useful Lives (Years)	12 years