Fair Value Measurements of Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Fair Value, Measurements, Recurring, USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Interest Rate Swap Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives	$ 8,307	$ 9,766
U.S. Government-sponsored agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	4,387	4,640
State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	159,872	158,194
U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	366,535	348,579
Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	367	224
Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,706	1,706
Interest Rate Swap Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	5,155	6,103
Interest Rate Cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	233	197
Significant Other Observable Inputs (Level 2) \| Interest Rate Swap Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives	8,307	9,766
Significant Other Observable Inputs (Level 2) \| U.S. Government-sponsored agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	4,387	4,640
Significant Other Observable Inputs (Level 2) \| State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	142,565	140,094
Significant Other Observable Inputs (Level 2) \| U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	366,535	348,579
Significant Other Observable Inputs (Level 2) \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,702	1,702
Significant Other Observable Inputs (Level 2) \| Interest Rate Swap Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	5,155	6,103
Significant Other Observable Inputs (Level 2) \| Interest Rate Cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	233	197
Significant Unobservable Inputs (Level 3) \| Interest Rate Swap Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives
Significant Unobservable Inputs (Level 3) \| State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	17,307	18,100
Significant Unobservable Inputs (Level 3) \| Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	367	224
Significant Unobservable Inputs (Level 3) \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	4	4
Significant Unobservable Inputs (Level 3) \| Interest Rate Swap Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives
Significant Unobservable Inputs (Level 3) \| Interest Rate Cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives

This element represents the portion of the balance sheet assertion valued at fair value by the entity whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission. This item represents Available-for-sale Securities which consist of all investments in certain debt and equity securities neither classified as trading or held-to-maturity securities. A debt security represents a creditor relationship with an enterprise. Debt securities include, among other items, US Treasury securities, US government securities, municipal securities, corporate bonds, convertible debt, commercial paper, and all securitized debt instruments. An equity security represents an ownership interest in an enterprise or the right to acquire or dispose of an ownership interest in an enterprise at fixed or determinable prices. Equity securities include, among other things, common stock, certain preferred stock, warrant rights, call options, and put options, but do not include convertible debt. An entity may opt to provide the reader with additional narrative text to better understand the nature of investments in debt and equity securities which are categorized as Available-for-sale.

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Fair value of derivative asset, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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- Definition

Fair value of derivative liability, presented on a gross basis even when the derivative instrument is subject to master netting arrangements and qualifies for net presentation in the statement of financial position.

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