Pension and Other Postretirement Benefits (Details 10) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2011
Defined benefit pension plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Estimated future employer contributions in next fiscal year	$ 25,700
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2012	26,938
2013	27,296
2014	27,729
2015	28,178
2016	28,585
Years 2017-2021	147,981
Total	286,707
Other postretirement benefit plans [Member]
Defined Benefit Plan, Estimated Future Benefit Payments [Abstract]
2012	5,314
2013	5,209
2014	5,338
2015	5,110
2016	4,855
Years 2017-2021	21,544
Total	$ 47,370

The employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph g

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e1928-114920

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant