Benefit Plans Benefit Plans - Health Care Cost Trends (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Healthcare cost trend rate assumed for next year	7.50%	7.50%
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate)	5.00%	5.00%
Year that rate reaches ultimate trend rate	2020	2019
Defined Benefit Plan, Effect of One-Percentage Point Change in Assumed Health Care Cost Trend Rates [Abstract]
Effect on total of service and interest cost, One Percentage-Point Increase	$ 34
Effect on total of service and interest cost, One Percentage-Point Decrease	(32)
Effect on postretirement benefit obligation, One Percentage-Point Increase	928
Effect on postretirement benefit obligation, One Percentage-Point Decrease	$ (836)

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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.

+ References

+ Details

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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

+ Details

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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.

+ References

+ Details

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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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- 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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