Fair Value Measurements - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) (Assets and Liabilities Measured at Fair Value on a Recurring Basis [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	$ 49,319	$ 48,369
Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value		718
Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	49,319	47,651
Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Cash Equivalents [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	6,902	5,101
Cash Equivalents [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Cash Equivalents [Member] | Significant Other Observable Inputs (Level 2) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	6,902	5,101
Cash Equivalents [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | U.S. government and government agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	28,185	28,854
Available-for-sale debt securities [Member] | Mortgage-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	5,222	2,999
Available-for-sale debt securities [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	3,299	3,213
Available-for-sale debt securities [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	1,614	598
Available-for-sale debt securities [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	4,097	6,886
Available-for-sale debt securities [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member] | U.S. government and government agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member] | Mortgage-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | U.S. government and government agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	28,185	28,854
Available-for-sale debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Mortgage-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	5,222	2,999
Available-for-sale debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	3,299	3,213
Available-for-sale debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	1,614	598
Available-for-sale debt securities [Member] | Significant Other Observable Inputs (Level 2) [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value	4,097	6,886
Available-for-sale debt securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | U.S. government and government agency obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Mortgage-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Available-for-sale debt securities [Member] | Significant Unobservable Inputs (Level 3) [Member] | Corporate Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value		718
Other [Member] | Quoted Prices in Active Markets for Identical Instruments (Level 1) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value		718
Other [Member] | Significant Unobservable Inputs (Level 3) [Member]
Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items]
Total assets measured at fair value