Benefit Obligations (Details 12)	Dec. 31, 2011	Dec. 31, 2010
Pension Benefits [Member]
Plan asset allocations for defined benefit pension plans and post-retirement benefit plan
Equity securities	54.00%	57.00%
Debt securities	42.00%	38.00%
Real estate securities	4.00%	5.00%
Non-qualified Pension Benefits [Member]
Plan asset allocations for defined benefit pension plans and post-retirement benefit plan
Equity securities	34.00%	35.00%
Debt securities	66.00%	65.00%
Real estate securities	0.00%	0.00%
Post-retirement Benefits [Member]
Plan asset allocations for defined benefit pension plans and post-retirement benefit plan
Equity securities	40.00%	40.00%
Debt securities	60.00%	60.00%
Real estate securities	0.00%	0.00%

The percentage of the fair value of equity securities to the fair value of total plan assets held as of the measurement date.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

-Subparagraph d(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 5

-Subparagraph (c)

-URI http://asc.fasb.org/extlink&oid=6962843&loc=d3e2446-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (d)(1)

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

Name:	us-gaap_DefinedBenefitPlanEquitySecurities
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant