Segment Information (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2012	Jul. 31, 2011
Segment Information (Textual) [Abstract]
Intercompany sales	$ 63.2	$ 47.9	$ 118.3	$ 90.6

Amount of revenue from transactions with other operating segments of the same entity.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 131

-Paragraph 27

-Subparagraph b

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Name:	us-gaap_RevenuesFromTransactionsWithOtherOperatingSegmentsOfSameEntity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration