XML 26 R18.htm IDEA: XBRL DOCUMENT v2.4.0.8

Marketable Securities - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014	Mar. 31, 2013	Sep. 30, 2013
Marketable Securities [Abstract]
Net unrealized gains (losses)	$ 210,000	$ 1,470,000	$ 704,000	$ 1,307,000
Transfers of investments between Level 1 and Level 2	0	0	0	0
Estimated interest accrued					$ 399,000

X

- Definition

Marketable securities estimated interest accrued.

+ References

No definition available.

+ Details

Name:	genc_MarketableSecuritiesEstimatedInterestAccrued
Namespace Prefix:	genc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Amount of transfers of assets measured on a recurring basis out of Level 1 of the fair value hierarchy into Level 2.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 820

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (bb)

-URI http://asc.fasb.org/extlink&oid=25499696&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueAssetsLevel1ToLevel2TransfersAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Details

Name:	us-gaap_MarketableSecuritiesAbstract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The sum of the realized and unrealized net gain (loss) on trading securities during the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Trading Securities

-URI http://asc.fasb.org/extlink&oid=6526789

+ Details

Name:	us-gaap_NetRealizedOrUnrealizedGainLossOnTradingSecurities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration