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.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 29, 30

-Article 5

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 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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 04

-Article 3

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Research Bulletin (ARB)

-Number 43

-Chapter 1

-Section B

-Paragraph 11A

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

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

Shareholders' Equity (Narrative) (Details) (USD $) In Millions, except Share data	1 Months Ended	3 Months Ended		9 Months Ended		45 Months Ended
	Jan. 31, 2008	Sep. 30, 2011	Oct. 01, 2010	Sep. 30, 2011	Oct. 01, 2010	Sep. 30, 2011
Shareholder's Equity [Line Items]
Stock repurchase program, authorized amount	$ 250.0
Stock repurchased during period, shares		0	216,000	0	2,576,000	6,819,000
Common stock open market average purchase price per share			$ 28.40		$ 28.67	$ 29.29
Stock repurchased during period, value			6.1		73.8	199.7
Stock repurchase program, remaining authorized repurchase fund				100.0
2008 Stock Repurchase Program [Member]
Shareholder's Equity [Line Items]
Stock repurchase program, remaining authorized repurchase fund				$ 0