Calculation for Basic and Diluted Earnings per Common Share (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Calculation For Basic And Diluted Earnings Per Common Share [Line Items]
Net income	$ 5,725	$ 7,141
Dividends on preferred stock	228	258
Net income available to common shareholders	$ 5,497	$ 6,883
Weighted average number of common shares outstanding, basic	18,423,123	20,032,694
Convertible preferred stock	1,048,486	1,202,049
Contingently issuable shares	11,672
Weighted average number of common shares outstanding, diluted	19,506,647	21,258,490
Basic earnings per common share	$ 0.30	$ 0.34
Diluted earnings per common share	$ 0.29	$ 0.34
Stock Option
Calculation For Basic And Diluted Earnings Per Common Share [Line Items]
Stock attributable to share based compensation	22,636	17,101
Total potential antidilutive shares	245,030	337,693
Restricted Stock
Calculation For Basic And Diluted Earnings Per Common Share [Line Items]
Stock attributable to share based compensation	730	6,646