Available-for-Sale Securities - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended	12 Months Ended
Sep. 30, 2012	Jun. 30, 2012
Period of unrealized losses for the available-for-sale securities	Twelve months or more
Impairment losses	$ 0	$ 0

The amount by which the fair value of an investment is less than the amortized cost basis or carrying amount of that investment at the balance sheet date and the decline in fair value is deemed to be other than temporary, before considering whether or not such amount is recognized in earnings or other comprehensive income.

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+ Details