Fair Value Measurements - Financial Assets Measured at Fair Value on Recurring Basis (Detail) - Fair Value, Measurements, Recurring - USD ($) $ in Thousands		Sep. 30, 2016	Sep. 30, 2015
Assets:
Total		$ 11,456	$ 10,006
Cash
Assets:
Cash equivalents	[1]	440	439
Marketable securities
Assets:
Marketable securities	[2]	11,016	9,567
Active Markets for Identical Instruments (Level 1)
Assets:
Total		11,456	10,006
Active Markets for Identical Instruments (Level 1) | Cash
Assets:
Cash equivalents	[1]	440	439
Active Markets for Identical Instruments (Level 1) | Marketable securities
Assets:
Marketable securities	[2]	$ 11,016	$ 9,567

[1] Included in cash and cash equivalents on our balance sheet at September 30, 2016 and 2015. Not included in this table are cash deposits of $75.5 million and $85.7 million at September 30, 2016 and 2015, 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, 2016 and 2015.