Amortized Cost and Fair Value of Debt Securities by Contractual Maturity (Detail) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012
Amortized cost
Due in one year or less	$ 832
Due after one year through five years	6,537
Due after five years through ten years	19,406
Due after ten years	43,675
Available for sale Securities, Debt Maturities, with Single Maturity Date, Amortized Cost, Total	70,450
Mortgage-backed securities and CMO	46,966
Available-for-sale Securities, Debt Maturities, Amortized Cost Basis, Total	117,416
Fair Value
Due in one year or less	835
Due after one year through five years	6,669
Due after five years through ten years	19,859
Due after ten years	45,146
Available for sale Securities, Debt Maturities, with Single Maturity Date, Fair Value, Total	72,509
Mortgage-backed securities and CMO	47,565
Available-for-sale Securities, Debt Securities, Total	120,074
Amortized cost
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years
Due after ten years	0
Held-to-maturity Securities, Debt Maturities, with Single Maturity Date, Net Carrying Amount, Total	0
Mortgage-backed securities and CMO	14
Held-to-maturity Securities, Debt Maturities, Net Carrying Amount, Total	14
Fair Value
Due in one year or less	0
Due after one year through five years	0
Due after five years through ten years
Due after ten years	0
Held-to-maturity Securities, Debt Maturities, with Single Maturity Date, Fair Value, Total	0
Mortgage-backed securities and CMO	14
Held-to-maturity Securities, Debt Maturities, Fair Value, Total	$ 14