Pension Plans, Retirement Benefits and Savings Plans (details) - Assumptions (USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Defined benefit plan disclosure
Assumptions used to determine benefit obligations, discount rate (percent)	4.10%	4.96%
Assumptions used to determine benefit obligations, future compensation increase rate (percent)	4.00%	4.00%
Assumptions used to determine net periodic benefit cost, discount rate (percent)	4.96%	4.15%
Pension Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	7.50%	7.50%
Postretirement Benefit Plans [Member]
Defined benefit plan disclosure
Assumptions used to determine net periodic benefit cost, expected long-term rate of return on assets (percent)	4.00%	4.00%
Assumed health care cost trend rates, rate to which the cost trend rate is assumed to decline (ultimate trend rate) (percent)	5.00%	5.00%
Impact to accumulated postretirement benefit obligation from increasing the assumed health care cost trend rate by 1%	29
Impact to the aggregate of the service and interest cost components of net postretirement benefit expense from increasing the assumed health care cost trend rate by 1%	1
Impact to accumulated postretirement benefit obligation from decreasing the assumed health care cost trend rate by 1%	24
Impact to the aggregate of the service and interest cost components of net postretirement benefit expense from decreasing the assumed health care cost trend rate by 1%	1
Postretirement Benefit Plan Before Age 65 [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	7.00%	7.25%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2022	2022
Postretirement Benefit Plan Age 65 and Older [Member]
Defined benefit plan disclosure
Assumed health care cost trend rates, medical, following year (percent)	6.50%	6.75%
Assumed health care cost trend rates, medical, year that the rate reaches the ultimate trend rate	2020	2020

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

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- Definition

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

+ References

+ Details

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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 30

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

-URI http://asc.fasb.org/extlink&oid=6512013

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (k)(3)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

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+ Details

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- Definition

Amount of effect of a one-percentage-point decrease in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

+ References

+ Details

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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the accumulated postretirement benefit obligation for health care benefits.

+ References

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- Definition

The effect of a one-percentage-point increase in the assumed health care cost trend rates on the aggregate of the service and interest cost components of net periodic postretirement health care benefit costs.

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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 Accounting Standards Codification

-Topic 715

-SubTopic 20

-Section 50

-Paragraph 1

-Subparagraph (l)

-URI http://asc.fasb.org/extlink&oid=35743120&loc=d3e1928-114920

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Health Care Cost Trend Rate

-URI http://asc.fasb.org/extlink&oid=6514820

+ Details

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- Definition

The ultimate trend rate for health care costs.

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+ Details

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- Definition

Year the ultimate health care cost trend rate is expected to be reached, in CCYY format.

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+ Details

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