Components of Net Periodic Pension Benefit Cost (Details Textual) (USD $) In Millions, unless otherwise specified	3 Months Ended	6 Months Ended
Jun. 30, 2012	Jun. 30, 2012
Components of Net Periodic Pension Benefit Cost (Textual) [Abstract]
Contribution towards frozen pension plan	$ 1.3	$ 2.4
Expected benefit payments under supplemental pension plans in the second half of 2012	0.6	0.6
Maximum [Member]
Defined Benefit Plan Disclosure [Line Items]
Prospective pension contribution in second half of 2012		13.7
Minimum [Member]
Defined Benefit Plan Disclosure [Line Items]
Prospective pension contribution in second half of 2012		$ 11.9

The increase in the fair value of plan assets from contributions made by the employer.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (b)(3)

-URI http://asc.fasb.org/extlink&oid=21915506&loc=d3e1928-114920

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