Number of shares that have been repurchased during the period and are being held in treasury.

Reference 1: 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 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher AICPA
-Name Accounting Principles Board Opinion (APB)
-Number 12
-Paragraph 10
-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 04
-Article 3

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 29, 30
-Article 5

Name:	us-gaap_TreasuryStockSharesAcquired
Namespace Prefix:	us-gaap
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

Treasury stock (Details) In Millions	3 Months Ended		9 Months Ended		9 Months Ended
Treasury stock (Details) In Millions	Jun. 30, 2011	Mar. 31, 2011	Jun. 30, 2011	Jun. 30, 2011	Jun. 30, 2011 Repurchase of Equity [Member]	Jun. 30, 2011 Common Stock Repurchase Program 10B5 1 [Member]
Equity, Class of Treasury Stock [Line Items]
Treasury Stock, Shares, Acquired	0	1.0	1.0
Subsequent Event, Amount, Shares					1.3
Stock Repurchase Program, Remaining Number of Shares Authorized to be Repurchased				5.7		0.7