Shareholders' Equity And Earnings Per Share (Narrative) (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	1 Months Ended	3 Months Ended		0 Months Ended	12 Months Ended	1 Months Ended
	Jan. 31, 2015	Mar. 31, 2015	Mar. 31, 2014	Dec. 19, 2008	Dec. 31, 2014	Mar. 31, 2012
Temporary Equity [Line Items]
Preferred stock, value		$ 126,427	$ 126,477		126,467
Cash dividends declared per common share (in usd per share)	$ 0.11	$ 0.11	$ 0.10
Common Stock Dividends Per Share Declared Annualized	$ 0.44
Dividends Payable, Date to be Paid	Feb. 19, 2015
Dividends Payable, Date of Record	Feb. 05, 2015
Delavan Bancshares
Temporary Equity [Line Items]
Common stock, shares issued, acquisition	422,121
US Treasury [Member]
Temporary Equity [Line Items]
Warrants outstanding		937,417		1,643,295
Investment Warrants, Exercise Price				$ 22.82
Warrant Termination Period				10 years
Warrants Exercised		0			705,878
Common Stock, Shares, Issued from Exercise of Warrant Shares					363,155
Series C Preferred Stock [Member]
Temporary Equity [Line Items]
Preferred stock, shares issued						126,500
Preferred stock, liquidation value per share		$ 1,000	$ 1,000		1,000	$ 1,000
Preferred stock, value						$ 126,500
Preferred Stock, Dividend Payment Terms						quarterly
Preferred stock, dividend rate, percentage						5.00%
Convertible Preferred Stock, Terms of Conversion						24.3132
Preferred Stock, Shares Converted		40			10
Common Stock, Shares, Conversion of Preferred Stock		972			244