Retirement Plans (Details 2)	12 Months Ended
Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Funded and Unfunded Pension Plans [Member]
Weighted-average assumptions used to determine benefit obligations at December 31
Discount rate	4.30%	5.30%	5.80%
Rate of compensation increase	4.30%	4.40%	4.30%
Weighted-average assumptions used to determine net benefit cost for years ended December 31
Discount rate	5.30%	5.80%	6.30%
Expected return on plan assets	7.50%	7.50%	7.50%
Rate of compensation increase	4.40%	4.30%	4.40%
Assumptions used to determine benefit obligations at December 31
Discount rate	4.30%	5.30%	5.80%
Postretirement Medical Plan [Member]
Weighted-average assumptions used to determine benefit obligations at December 31
Discount rate	3.90%	4.80%	5.40%
Assumptions used to determine benefit obligations at December 31
Discount rate	3.90%	4.80%	5.40%
Initial health care trend rate	8.00%	8.00%	8.00%
Ultimate trend rate	5.00%	5.00%	4.50%
Year in which ultimate trend rate is reached	2018	2017	2013

Year in which ultimate trend rate is reached.

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- Definition

The interest rate used to adjust for the time value of money for the plan.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

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-Name Accounting Standards Codification

-Topic 715

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- Definition

Expected rate of compensation increases (for pay-related plans).

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-Name Statement of Financial Accounting Standard (FAS)

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- Definition

The interest rate used to adjust for the time value of money.

+ References

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- Definition

An assumption as to the rate of return on plan assets reflecting the average rate of earnings expected on the funds invested or to be invested to provide for the benefits included in the benefit obligation.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

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-Paragraph 1

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-Number 87

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Expected Long-Term Rate of Return on Plan Assets

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- Definition

Expected rate of compensation increases (for pay-related plans).

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

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- Definition

The assumed health care cost trend rate for the next year used to measure the expected cost of benefits covered by the plan (gross eligible charges). This is based upon the annual rate of change in the cost of health care benefits currently provided by the postretirement benefit plan, due to factors other than changes in the composition of the plan population by age and dependency status.

+ References

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

-Paragraph 5

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-Publisher FASB

-Name Accounting Standards Codification

-Glossary Health Care Cost Trend Rate

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- Definition

The ultimate trend rate for health care costs.

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-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 132R

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