Share-Based Payment Arrangements (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Share-Based Payment Arrangements (Textual) [Abstract]
Share-based compensation expense, net of tax	$ 2.0	$ 2.3
Stock options exercised	1,088,428
Weighted average exercise price	$ 32.84
Stock options forfeited or expired	4,313

Number of share options (or share units) exercised during the current period.

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

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-Name Accounting Standards Codification

-Topic 505

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