Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Securities Available For Sale:
Securities available for sale	$ 724,298	$ 737,311
Trading Securities:
Trading securities	4,729	4,459
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities Available For Sale:
Securities available for sale	74,661	54,169
Trading Securities:
Trading securities	4,574	4,300
Liabilities:
Interest rate swaps	0	0
Significant Other Observable Inputs (Level 2) [Member]
Securities Available For Sale:
Securities available for sale	649,007	680,562
Trading Securities:
Trading securities	155	159
Liabilities:
Interest rate swaps	(1,253)	(1,745)
Significant Unobservable Inputs (Level 3) [Member]
Securities Available For Sale:
Securities available for sale	630	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	724,298	737,311
Trading Securities:
Trading securities	4,729	4,459
Fair Value Measurement on Recurring Basis [Member] \| U.S. Treasury [Member]
Securities Available For Sale:
Securities available for sale	2,016	4,036
Fair Value Measurement on Recurring Basis [Member] \| U.S. Government Sponsored Entities [Member]
Securities Available For Sale:
Securities available for sale	180,062	163,781
Trading Securities:
Trading securities	54	58
Fair Value Measurement on Recurring Basis [Member] \| States and Political Subdivisions [Member]
Securities Available For Sale:
Securities available for sale	181,235	181,279
Fair Value Measurement on Recurring Basis [Member] \| Residential & Multi Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	271,337	316,822
Fair Value Measurement on Recurring Basis [Member] \| Commercial Mortgage [Member]
Securities Available For Sale:
Securities available for sale	983	1,304
Fair Value Measurement on Recurring Basis [Member] \| Corporate Notes and Bonds [Member]
Securities Available For Sale:
Securities available for sale	13,374	15,024
Trading Securities:
Trading securities	101	101
Fair Value Measurement on Recurring Basis [Member] \| Pooled Trust Preferred [Member]
Securities Available For Sale:
Securities available for sale	630	600
Fair Value Measurement on Recurring Basis [Member] \| Pooled SBA [Member]
Securities Available For Sale:
Securities available for sale	73,663	52,927
Fair Value Measurement on Recurring Basis [Member] \| Other Securities [Member]
Securities Available For Sale:
Securities available for sale	998	1,538
Fair Value Measurement on Recurring Basis [Member] \| Corporate Equity Securities [Member]
Trading Securities:
Trading securities	3,432	3,117
Fair Value Measurement on Recurring Basis [Member] \| Certificates of Deposit [Member]
Trading Securities:
Trading securities	354	408
Fair Value Measurement on Recurring Basis [Member] \| International Mutual Funds [Member]
Trading Securities:
Trading securities	273	287
Fair Value Measurement on Recurring Basis [Member] \| Large Cap Growth Mutual Funds [Member]
Trading Securities:
Trading securities	164	157
Fair Value Measurement on Recurring Basis [Member] \| Money Market Mutual Funds [Member]
Trading Securities:
Trading securities		110
Fair Value Measurement on Recurring Basis [Member] \| Large Cap Value Mutual Funds [Member]
Trading Securities:
Trading securities	106	104
Fair Value Measurement on Recurring Basis [Member] \| Real Estate Investment Trust Mutual Funds [Member]
Trading Securities:
Trading securities	102	65
Fair Value Measurement on Recurring Basis [Member] \| Small Cap Mutual Funds [Member]
Trading Securities:
Trading securities	56	26
Fair Value Measurement on Recurring Basis [Member] \| Mid Cap Mutual Funds [Member]
Trading Securities:
Trading securities	68	26
Fair Value Measurement on Recurring Basis [Member] \| Mid Cap Mutual Funds Two [Member]
Trading Securities:
Trading securities	19
Fair Value Measurement on Recurring Basis [Member] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	(1,253)	(1,745)
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	74,661	54,169
Trading Securities:
Trading securities	4,574	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 & 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	73,663	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	998	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	3,432	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	354	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	273	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	164	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		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	106	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	102	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	56	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	68	26
Fair Value Measurement on Recurring Basis [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Mid Cap Mutual Funds Two [Member]
Trading Securities:
Trading securities	19
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] \| Significant Other Observable Inputs (Level 2) [Member]
Securities Available For Sale:
Securities available for sale	649,007	680,562
Trading Securities:
Trading securities	155	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	2,016	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	180,062	163,781
Trading Securities:
Trading securities	54	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	181,235	181,279
Fair Value Measurement on Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Residential & Multi Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	271,337	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	983	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	13,374	13,044
Trading Securities:
Trading securities	101	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
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] \| Mid Cap Mutual Funds Two [Member]
Trading Securities:
Trading securities	0
Fair Value Measurement on Recurring Basis [Member] \| Significant Other Observable Inputs (Level 2) [Member] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	(1,253)	(1,745)
Fair Value Measurement on Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Securities Available For Sale:
Securities available for sale	630	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 & 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	630	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
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] \| Mid Cap Mutual Funds Two [Member]
Trading Securities:
Trading securities	0
Fair Value Measurement on Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	$ 0	$ 0