Fair Value - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013
Securities Available For Sale:
Securities available for sale	$ 699,366	$ 685,991
Trading Securities:
Trading securities	4,440	4,127
Quoted Prices in Active Markets for Identical Assets (Level 1) [Member]
Securities Available For Sale:
Securities available for sale	997	985
Trading Securities:
Trading securities	4,182	3,923
Liabilities:
Interest rate swaps	0	0
Significant Other Observable Inputs (Level 2) [Member]
Securities Available For Sale:
Securities available for sale	697,498	684,345
Trading Securities:
Trading securities	258	204
Liabilities:
Interest rate swaps	(936)	(1,116)
Significant Unobservable Inputs (Level 3) [Member]
Securities Available For Sale:
Securities available for sale	871	661
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	699,366	685,991
Trading Securities:
Trading securities	4,440	4,127
Fair Value Measurement on Recurring Basis [Member] \| U.S. Government Sponsored Entities [Member]
Securities Available For Sale:
Securities available for sale	164,772	181,625
Trading Securities:
Trading securities	54	52
Fair Value Measurement on Recurring Basis [Member] \| States and Political Subdivisions [Member]
Securities Available For Sale:
Securities available for sale	181,561	177,943
Fair Value Measurement on Recurring Basis [Member] \| Residential and Multi-Family Mortgage [Member]
Securities Available For Sale:
Securities available for sale	271,650	242,607
Fair Value Measurement on Recurring Basis [Member] \| Commercial Mortgage [Member]
Securities Available For Sale:
Securities available for sale	0	374
Fair Value Measurement on Recurring Basis [Member] \| Corporate Notes and Bonds [Member]
Securities Available For Sale:
Securities available for sale	14,712	14,075
Trading Securities:
Trading securities	204	152
Fair Value Measurement on Recurring Basis [Member] \| Pooled Trust Preferred [Member]
Securities Available For Sale:
Securities available for sale	871	661
Fair Value Measurement on Recurring Basis [Member] \| Pooled SBA [Member]
Securities Available For Sale:
Securities available for sale	64,803	67,721
Fair Value Measurement on Recurring Basis [Member] \| Other Securities [Member]
Securities Available For Sale:
Securities available for sale	997	985
Fair Value Measurement on Recurring Basis [Member] \| Corporate Equity Securities [Member]
Trading Securities:
Trading securities	3,009	2,705
Fair Value Measurement on Recurring Basis [Member] \| Mutual Funds [Member]
Trading Securities:
Trading securities	919	965
Fair Value Measurement on Recurring Basis [Member] \| Certificates of Deposit [Member]
Trading Securities:
Trading securities	254	253
Fair Value Measurement on Recurring Basis [Member] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	(936)	(1,116)
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	997	985
Trading Securities:
Trading securities	4,182	3,923
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	0	0
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	997	985
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	3,009	2,705
Fair Value Measurement on Recurring Basis [Member] \| Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] \| Mutual Funds [Member]
Trading Securities:
Trading securities	919	965
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	254	253
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	697,498	684,345
Trading Securities:
Trading securities	258	204
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	164,772	181,625
Trading Securities:
Trading securities	54	52
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	181,561	177,943
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	271,650	242,607
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	0	374
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	14,712	14,075
Trading Securities:
Trading securities	204	152
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	64,803	67,721
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] \| Mutual Funds [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] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	(936)	(1,116)
Fair Value Measurement on Recurring Basis [Member] \| Significant Unobservable Inputs (Level 3) [Member]
Securities Available For Sale:
Securities available for sale	871	661
Trading Securities:
Trading securities	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	0
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	871	661
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] \| Mutual Funds [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] \| Interest Rate Swaps [Member]
Liabilities:
Interest rate swaps	$ 0	$ 0