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	Sep. 30, 2012	Dec. 31, 2011
Interest Rate Swap Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives	$ (10,406)	$ (7,797)
U.S. Government-sponsored agency securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	4,782	117
State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	161,017	147,353
U.S. Government-sponsored mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	383,912	368,998
Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	202	193
Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,706	1,830
Interest Rate Swap Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	6,412	5,241
Interest Rate Cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	206	424
Significant Other Observable Inputs (Level 2) \| Interest Rate Swap Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives	(10,406)
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	4,782	117
Significant Other Observable Inputs (Level 2) \| State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	142,798	126,712
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	383,912	368,998
Significant Other Observable Inputs (Level 2) \| Equity Securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	1,702	1,826
Significant Other Observable Inputs (Level 2) \| Interest Rate Swap Assets
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	6,412
Significant Other Observable Inputs (Level 2) \| Interest Rate Cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives	206
Significant Unobservable Inputs (Level 3) \| Interest Rate Swap Liabilities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Liability derivatives		(7,797)
Significant Unobservable Inputs (Level 3) \| State and municipal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	18,219	20,641
Significant Unobservable Inputs (Level 3) \| Corporate obligations
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	202	193
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		5,241
Significant Unobservable Inputs (Level 3) \| Interest Rate Cap
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Asset derivatives		$ 424

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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