Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Assets and Liabilities Measured at Fair Value on a Recurring Basis, USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	$ 49,583	$ 48,369
Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	6,002	5,101
Available-for-sale debt securities | U.S. government and government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	33,150	28,854
Available-for-sale debt securities | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	2,743	2,999
Available-for-sale debt securities | Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	3,701	3,213
Available-for-sale debt securities | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	549	598
Available-for-sale debt securities | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	2,439	6,886
Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	999	718
Quoted Prices in Active Markets for Identical Instruments (Level 1)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	999	718
Quoted Prices in Active Markets for Identical Instruments (Level 1) | Other
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	999	718
Significant Other Observable Inputs (Level 2)
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	48,584	47,651
Significant Other Observable Inputs (Level 2) | Cash Equivalents
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	6,002	5,101
Significant Other Observable Inputs (Level 2) | Available-for-sale debt securities | U.S. government and government agency obligations
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	33,150	28,854
Significant Other Observable Inputs (Level 2) | Available-for-sale debt securities | Mortgage-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	2,743	2,999
Significant Other Observable Inputs (Level 2) | Available-for-sale debt securities | Municipal Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	3,701	3,213
Significant Other Observable Inputs (Level 2) | Available-for-sale debt securities | Asset-backed securities
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	549	598
Significant Other Observable Inputs (Level 2) | Available-for-sale debt securities | Corporate Bonds
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	$ 2,439	$ 6,886