Percentage held common stock outstanding.

No definition available.

Name:	gff_PercentageHeldCommonStockOutstanding
Namespace Prefix:	gff_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	gff_RELATEDPARTIESDetailsLineItems
Namespace Prefix:	gff_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The price per share of the common shares repurchased during the period.

+ References

No definition available.

+ Details

Name:	gff_StockRepurchasedDuringPeriodPerShare
Namespace Prefix:	gff_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Stock Repurchased During Period, Share Price Discount Rate

+ References

No definition available.

+ Details

Name:	gff_StockRepurchasedDuringPeriodSharePriceDiscountRate
Namespace Prefix:	gff_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Costs of sales and operating expenses for the period incurred from transactions with related parties.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.2)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

+ Details

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

- Definition

Number of shares issued which are neither cancelled nor held in the treasury.

+ References

No definition available.

+ Details

Name:	us-gaap_SharesOutstanding
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of shares that have been repurchased during the period and have not been retired and are not held in treasury. Some state laws may govern the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 505

-SubTopic 10

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Equity impact of the value of stock that has been repurchased during the period and has not been retired and is not held in treasury. Some state laws may mandate the circumstances under which an entity may acquire its own stock and prescribe the accounting treatment therefore. This element is used when state law does not recognize treasury stock.

+ References

+ Details

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

RELATED PARTIES (Details) (USD $)	0 Months Ended		12 Months Ended				48 Months Ended
RELATED PARTIES (Details) (USD $)	Dec. 10, 2013	Nov. 12, 2013	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2014
RELATED PARTIES (Details) [Line Items]
Co-manager fees						$ 825,000
Stock repurchased during period, shares (in Shares)	4,444,444		1,906,631	2,369,786	1,187,066		6,994,862
Stock repurchased during period, value	$ 50,000,000		$ 23,167,000	$ 26,285,000	$ 10,379,000		$ 72,197,000
Stock repurchased during period per share (in Dollars per share)	$ 11.25		$ 12.15	$ 11.09	$ 8.74		$ 10.32
Stock repurchased during period, share price discount rate		9.20%
GS Direct [Member]
RELATED PARTIES (Details) [Line Items]
Shares, outstanding	5,560,000
Percentage held common stock outstanding	10.00%