Fair Value Measurements - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring [Member] - USD ($) $ in Thousands		Sep. 30, 2015	Sep. 30, 2014
Assets:
Total		$ 10,006	$ 19,077
Cash
Assets:
Cash equivalents	[1]	439	10,326
Marketable securities
Assets:
Marketable securities available-for-sale	[2]	9,567	8,751
Active Markets for Identical Instruments (Level 1)
Assets:
Total		10,006	19,077
Active Markets for Identical Instruments (Level 1) | Cash
Assets:
Cash equivalents	[1]	439	10,326
Active Markets for Identical Instruments (Level 1) | Marketable securities
Assets:
Marketable securities available-for-sale	[2]	$ 9,567	$ 8,751

[1] Included in cash and cash equivalents on our balance sheet at September 30, 2015 and 2014. Not included in this table are cash deposits of $85.7 million and $94.7 million at September 30, 2015 and 2014, respectively.

[2] Represents securities held under a supplemental retirement and savings plan for certain officers and senior management employees, which are distributed upon termination or retirement of the employees. Included in long-term marketable securities on our balance sheet at September 30, 2015 and 2014.