Marketable Securities - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Sep. 30, 2013
Marketable Securities [Abstract]
Net unrealized gains (losses)	$ 1,334,000	$ (832,000)	$ 2,038,000	$ 475,000
Transfers of investments between Level 1 and Level 2	0	0	0	0
Estimated interest accrued					$ 399,000