CONSOLIDATED STATEMENTS OF CASH FLOWS (Parenthetical) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 31, 2013	Mar. 31, 2012
CONSOLIDATED STATEMENTS OF CASH FLOWS
Proceeds from exercise of stock options, excess tax benefits of share based payments	$ 0.4	$ 0.2

Amount of excess tax benefit (tax deficiency) that arises when compensation cost from non-qualified share-based compensation recognized on the entity's tax return exceeds (is less than) compensation cost from equity-based compensation recognized in financial statements. Excess tax benefit (tax deficiency) increases (decreases) net cash provided by financing activities.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 20

-Section 55

-Paragraph 24

-URI http://asc.fasb.org/extlink&oid=6576910&loc=d3e11374-113907

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