Derivative Financial Instruments - Fair Value of Derivative Financial Instruments (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Asset Derivative	$ 1,198	$ 3,072
Total Liability Derivative	4,014	7,707
Derivatives Designated as Hedging Instruments [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Asset Derivative	579	2,214
Total Liability Derivative	4,014	7,707
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts One [Member] | Loans [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Asset Derivative	23	279
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts One [Member] | Other Liabilities [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Liability Derivative	579	2,214
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts Two [Member] | Other Assets [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Asset Derivative	556	1,935
Derivatives Designated as Hedging Instruments [Member] | Interest Rate Contracts Two [Member] | Other Liabilities [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Liability Derivative	3,435	5,493
Derivatives Not Designated as Hedging Instruments [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Asset Derivative	619	858
Total Liability Derivative
Derivatives Not Designated as Hedging Instruments [Member] | Mortgage Loan Contracts [Member] | Other Assets [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Asset Derivative	619	858
Derivatives Not Designated as Hedging Instruments [Member] | Mortgage Loan Contracts [Member] | Other Liabilities [Member]
Fair Values Of Financial Assets And Liabilities Including Derivative Financial Instruments [Line Items]
Total Liability Derivative