Fair Value Measurement of Assets and Liabilities - Assets and Liabilities Measured at Fair Value on Recurring and Non-Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	$ 783,205	$ 829,692
Trading securities	14,221	14,264
Loans held for sale		0
U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	91,887	84,665
U.S. Government Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	46,041	48,627
Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	38,015	37,700
Residential Mortgage-Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	478,132	508,029
Trust Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	20,650	19,215
Corporate and Other Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	84,536	83,398
Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	23,944	48,058
Fair Value [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	783,205	829,692
Trading securities	14,221	14,264
Loans held for sale	8,218	10,488
Other assets	14,499	15,122
Total assets	820,143
Other liabilities	26,666	20,586
Total Liabilities Fair Value Disclosure		20,586
Total liabilities	26,666
Total Assets Fair Value Disclosure		869,566
Fair Value [Member] | Recurring Fair Value Measurements [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	91,887	84,665
Fair Value [Member] | Recurring Fair Value Measurements [Member] | U.S. Government Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	46,041	48,627
Fair Value [Member] | Recurring Fair Value Measurements [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	38,015	37,700
Fair Value [Member] | Recurring Fair Value Measurements [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	478,132	508,029
Fair Value [Member] | Recurring Fair Value Measurements [Member] | Trust Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	20,650	19,215
Fair Value [Member] | Recurring Fair Value Measurements [Member] | Corporate and Other Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	84,536	83,398
Fair Value [Member] | Recurring Fair Value Measurements [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	23,944	48,058
Fair Value [Member] | Non-Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	7,850
Collateral dependent impaired loans	21,740	35,700
Loan servicing rights	2,314	3,677
Foreclosed assets	12,715	25,929
Total	44,619
Non Recurring Fair Value Measurements Asset Liability Total		65,306
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	121,530	138,843
Trading securities	0	0
Loans held for sale	0	0
Other assets	0	0
Total assets	121,530
Other liabilities	0	0
Total Liabilities Fair Value Disclosure		0
Total liabilities	0
Total Assets Fair Value Disclosure		138,843
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	91,887	84,665
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | U.S. Government Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | Trust Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | Corporate and Other Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	27,473	27,273
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Recurring Fair Value Measurements [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	2,170	26,905
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Non-Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	0
Collateral dependent impaired loans	0	0
Loan servicing rights	0	0
Foreclosed assets	0	0
Total	0
Non Recurring Fair Value Measurements Asset Liability Total		0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	635,646	662,326
Trading securities	14,221	14,264
Loans held for sale	8,218	10,488
Other assets	14,499	15,122
Total assets	672,584
Other liabilities	26,666	20,586
Total Liabilities Fair Value Disclosure		20,586
Total liabilities	26,666
Total Assets Fair Value Disclosure		702,200
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | U.S. Government Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	46,041	48,627
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	38,015	37,700
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	456,630	483,277
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | Trust Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	16,123	15,444
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | Corporate and Other Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	57,063	56,125
Significant Other Observable Inputs (Level 2) [Member] | Recurring Fair Value Measurements [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	21,774	21,153
Significant Other Observable Inputs (Level 2) [Member] | Non-Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	7,850
Collateral dependent impaired loans	0	0
Loan servicing rights	0	0
Foreclosed assets	0	0
Total	7,850
Non Recurring Fair Value Measurements Asset Liability Total		0
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	26,029	28,523
Trading securities		0
Loans held for sale	0	0
Other assets	0	0
Total assets	26,029
Other liabilities	0	0
Total Liabilities Fair Value Disclosure		0
Total liabilities	0
Total Assets Fair Value Disclosure		28,523
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | U.S. Treasury Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | U.S. Government Agency Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Obligations of States and Political Subdivisions [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Residential Mortgage-Backed Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	21,502	24,752
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Trust Preferred Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	4,527	3,771
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Corporate and Other Debt Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Recurring Fair Value Measurements [Member] | Equity Securities [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale	0	0
Significant Unobservable Inputs (Level 3) [Member] | Non-Recurring Fair Value Measurements [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans held for sale	0
Collateral dependent impaired loans	21,740	35,700
Loan servicing rights	2,314	3,677
Foreclosed assets	12,715	25,929
Total	36,769
Non Recurring Fair Value Measurements Asset Liability Total		$ 65,306