Investments - Amortized Cost, Unrealized Holding Gains (Losses) and Fair Value of Available-for-Sale Securities (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Sep. 30, 2012
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	$ 42,465	$ 42,186
Unrealized Gains	136	405
Unrealized Losses	(184)	(41)
Fair Value	42,417	42,550
U.S. government and government agency obligations [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	28,260	28,641
Unrealized Gains	15	213
Unrealized Losses	(90)
Fair Value	28,185	28,854
Mortgage-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	5,180	2,896
Unrealized Gains	92	129
Unrealized Losses	(50)	(26)
Fair Value	5,222	2,999
Municipal Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	3,288	3,178
Unrealized Gains	17	35
Unrealized Losses	(6)
Fair Value	3,299	3,213
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	1,622	613
Unrealized Gains
Unrealized Losses	(8)	(15)
Fair Value	1,614	598
Corporate Bonds [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized Cost	4,115	6,858
Unrealized Gains	12	28
Unrealized Losses	(30)
Fair Value	$ 4,097	$ 6,886