The adjustment to reduce the value of existing agreements that specify the lessee's rights to use the leased property. This expense is charged when the estimates of future profits generated by the leased property are reduced.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 28

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 360

-SubTopic 10

-Section 45

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=6390789&loc=d3e2420-110228

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

Operating Leases (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Operating Leased Assets [Line Items]
Operating Leases, Rent Expense	$ 8.4	$ 8.4	$ 6.6
Operating Leases, Rent Expense, Sublease Rentals	0.3	0.3	0.2
Impairment of Leasehold			0.5
Leaseholds and Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Impairment of Leasehold			1.5
Leaseholds Sublease Revenue [Member]
Operating Leased Assets [Line Items]
Impairment of Leasehold			1.0
Leasehold Improvements [Member]
Operating Leased Assets [Line Items]
Impairment of Leasehold			$ 0.5