Restricted Stock Additional Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2012 PBRSUs	Dec. 31, 2012 RSUs	Dec. 31, 2011 RSUs	Dec. 31, 2011 Restricted Stock	Dec. 31, 2010 Restricted Stock
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant-date fair value of shares granted	$ 1.4	$ 5.5	$ 4.5	$ 0.6	$ 1.4
Total fair value of shares vested		$ 0.8	$ 0.1		$ 1.4

Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (d)(2)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

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