Investments - Trading Investments Details (Detail) - USD ($) $ in Thousands	12 Months Ended
Sep. 30, 2016	Sep. 30, 2015
Investment [Line Items]
Cost	$ 4	$ 4
Gross Unrealized Gains	18	16
Gross Unrealized Losses	(14)	(13)
Total	8	7
Mutual Fund Investments [Member]
Investment [Line Items]
Cost	4	4
Gross Unrealized Gains	18	16
Gross Unrealized Losses	(14)	(13)
Total	$ 8	$ 7

Amount of unrealized holding loss before gain recognized in the income statement for investments in trading securities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 35
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=27723805&loc=d3e24584-111560

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.7(c))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Trading Securities
-URI http://asc.fasb.org/extlink&oid=6526789

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 9
-Subparagraph (e)
-URI http://asc.fasb.org/extlink&oid=73527792&loc=d3e27357-111563

Name:	us-gaap_TradingSecuritiesUnrealizedHoldingLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration