Litigation (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013 item
Litigation
Alleged tax deficiency including interest and penalties related to 2006 through 2008 tax years	$ 13.3
Liability or reserve recorded related to alleged tax deficiencies	$ 0
Number of subsidiaries to which alleged tax deficiencies are related	2

The estimated range of reasonably possible losses resulting from an adverse position taken by a taxing authority.

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

-Publisher FASB

-Name FASB Interpretation (FIN)

-Number 14

-Paragraph 3

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 740

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (d)(3)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32718-109319

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant