Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Securities Available For Sale:
Securities available for sale	$ 700,531	$ 737,311
Trading Securities:
Trading securities	4,358	4,459
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities Available For Sale:
Securities available for sale	70,509	54,169
Trading Securities:
Trading securities	4,153	4,300
Liabilities:
Interest rate swaps	0	0
Significant Other Observable Inputs (Level 2) [Member]
Securities Available For Sale:
Securities available for sale	629,246	680,562
Trading Securities:
Trading securities	205	159
Liabilities:
Interest rate swaps	(1,241)	(1,745)
Significant Unobservable Inputs (Level 3) [Member]
Securities Available For Sale:
Securities available for sale	776	2,580
Trading Securities:
Trading securities	0	0
Liabilities:
Interest rate swaps	0	0
Fair Value Measurement on Recurring Basis [Member]
Securities Available For Sale:
Securities available for sale	700,531	737,311
Trading Securities:
Trading securities	4,358	4,459
Fair Value Measurement on Recurring Basis [Member] | U.S. Treasury [Member]
Securities Available For Sale:
Securities available for sale	2,007	4,036
Fair Value Measurement on Recurring Basis [Member] | U.S. Government Sponsored Entities [Member]
Securities Available For Sale:
Securities available for sale	177,230	163,781
Trading Securities:
Trading securities	53	58
Fair Value Measurement on Recurring Basis [Member] | States and Political Subdivisions [Member]
Securities Available For Sale:
Securities available for sale	179,863	181,279
Fair Value Measurement on Recurring Basis [Member] | Residential and Multi Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	255,039	316,822
Fair Value Measurement on Recurring Basis [Member] | Commercial Mortgage [Member]
Securities Available For Sale:
Securities available for sale	950	1,304
Fair Value Measurement on Recurring Basis [Member] | Corporate Notes and Bonds [Member]
Securities Available For Sale:
Securities available for sale	14,157	15,024
Trading Securities:
Trading securities	152	101
Fair Value Measurement on Recurring Basis [Member] | Pooled Trust Preferred [Member]
Securities Available For Sale:
Securities available for sale	776	600
Fair Value Measurement on Recurring Basis [Member] | Pooled SBA [Member]
Securities Available For Sale:
Securities available for sale	69,513	52,927
Fair Value Measurement on Recurring Basis [Member] | Other Securities [Member]
Securities Available For Sale:
Securities available for sale	996	1,538
Fair Value Measurement on Recurring Basis [Member] | Corporate Equity Securities [Member]
Trading Securities:
Trading securities	2,998	3,117
Fair Value Measurement on Recurring Basis [Member] | Certificates of Deposit [Member]
Trading Securities:
Trading securities	253	408
Fair Value Measurement on Recurring Basis [Member] | International Mutual Funds [Member]
Trading Securities:
Trading securities	257	287
Fair Value Measurement on Recurring Basis [Member] | Large Cap Growth Mutual Funds [Member]
Trading Securities:
Trading securities	182	157
Fair Value Measurement on Recurring Basis [Member] | Money Market Mutual Funds [Member]
Trading Securities:
Trading securities	86	110
Fair Value Measurement on Recurring Basis [Member] | Large Cap Value Mutual Funds [Member]
Trading Securities:
Trading securities	121	104
Fair Value Measurement on Recurring Basis [Member] | Real Estate Investment Trust Mutual Funds [Member]
Trading Securities:
Trading securities	40	65
Fair Value Measurement on Recurring Basis [Member] | Small Cap Mutual Funds [Member]
Trading Securities:
Trading securities	81	26
Fair Value Measurement on Recurring Basis [Member] | Mid Cap Mutual Funds [Member]
Trading Securities:
Trading securities	81	26
Fair Value Measurement on Recurring Basis [Member] | Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	(1,241)	(1,745)
Fair Value Measurement on Recurring Basis [Member] | Commodities Mutual Funds [Member]
Trading Securities:
Trading securities	54
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities Available For Sale:
Securities available for sale	70,509	54,169
Trading Securities:
Trading securities	4,153	4,300
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Treasury [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | U.S. Government Sponsored Entities [Member]
Securities Available For Sale:
Securities available for sale	0	0
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | States and Political Subdivisions [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Residential and Multi Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commercial Mortgage [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Notes and Bonds [Member]
Securities Available For Sale:
Securities available for sale	0	0
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pooled Trust Preferred [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Pooled SBA [Member]
Securities Available For Sale:
Securities available for sale	69,513	52,631
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Other Securities [Member]
Securities Available For Sale:
Securities available for sale	996	1,538
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Corporate Equity Securities [Member]
Trading Securities:
Trading securities	2,998	3,117
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Certificates of Deposit [Member]
Trading Securities:
Trading securities	253	408
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | International Mutual Funds [Member]
Trading Securities:
Trading securities	257	287
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Large Cap Growth Mutual Funds [Member]
Trading Securities:
Trading securities	182	157
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Money Market Mutual Funds [Member]
Trading Securities:
Trading securities	86	110
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Large Cap Value Mutual Funds [Member]
Trading Securities:
Trading securities	121	104
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Real Estate Investment Trust Mutual Funds [Member]
Trading Securities:
Trading securities	40	65
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Small Cap Mutual Funds [Member]
Trading Securities:
Trading securities	81	26
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Mid Cap Mutual Funds [Member]
Trading Securities:
Trading securities	81	26
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	0	0
Fair Value Measurement on Recurring Basis [Member] | Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] | Commodities Mutual Funds [Member]
Trading Securities:
Trading securities	54
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member]
Securities Available For Sale:
Securities available for sale	629,246	680,562
Trading Securities:
Trading securities	205	159
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Treasury [Member]
Securities Available For Sale:
Securities available for sale	2,007	4,036
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. Government Sponsored Entities [Member]
Securities Available For Sale:
Securities available for sale	177,230	163,781
Trading Securities:
Trading securities	53	58
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | States and Political Subdivisions [Member]
Securities Available For Sale:
Securities available for sale	179,863	181,279
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Residential and Multi Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	255,039	316,822
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Commercial Mortgage [Member]
Securities Available For Sale:
Securities available for sale	950	1,304
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Notes and Bonds [Member]
Securities Available For Sale:
Securities available for sale	14,157	13,044
Trading Securities:
Trading securities	152	101
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Pooled Trust Preferred [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Pooled SBA [Member]
Securities Available For Sale:
Securities available for sale	0	296
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Other Securities [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Equity Securities [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Certificates of Deposit [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | International Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Large Cap Growth Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Money Market Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Large Cap Value Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Real Estate Investment Trust Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Small Cap Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mid Cap Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	(1,241)	(1,745)
Fair Value Measurement on Recurring Basis [Member] | Significant Other Observable Inputs (Level 2) [Member] | Commodities Mutual Funds [Member]
Trading Securities:
Trading securities	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member]
Securities Available For Sale:
Securities available for sale	776	2,580
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Treasury [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. Government Sponsored Entities [Member]
Securities Available For Sale:
Securities available for sale	0	0
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | States and Political Subdivisions [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Residential and Multi Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Commercial Mortgage [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate Notes and Bonds [Member]
Securities Available For Sale:
Securities available for sale	0	1,980
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Pooled Trust Preferred [Member]
Securities Available For Sale:
Securities available for sale	776	600
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Pooled SBA [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Other Securities [Member]
Securities Available For Sale:
Securities available for sale	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate Equity Securities [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Certificates of Deposit [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | International Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Large Cap Growth Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Money Market Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Large Cap Value Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Real Estate Investment Trust Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Small Cap Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mid Cap Mutual Funds [Member]
Trading Securities:
Trading securities	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	0	0
Fair Value Measurement on Recurring Basis [Member] | Significant Unobservable Inputs (Level 3) [Member] | Commodities Mutual Funds [Member]
Trading Securities:
Trading securities	$ 0