Employee Benefit Plans (Schedule of Health Care Costs Trend Rates) (Details)	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015
Pre Medicare Eligible Claims [Member]
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	10.00%	8.00%
Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate	10% down to 5% in 2024	8% down to 5% in 2020
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2024	2020
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%	5.00%
Medicare Eligible Claims [Member]
Defined Benefit Plan, Assumed Health Care Cost Trend Rates [Abstract]
Defined Benefit Plan, Health Care Cost Trend Rate Assumed for Next Fiscal Year	10.00%	8.00%
Defined Benefit Plan, Description of Direction and Pattern of Change for Assumed Health Care Cost Trend Rate	10% down to 5% in 2024	8% down to 5% in 2020
Defined Benefit Plan, Year that Rate Reaches Ultimate Trend Rate	2024	2020
Defined Benefit Plan, Ultimate Health Care Cost Trend Rate	5.00%	5.00%

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- Definition

A general description of the direction and pattern of change in the assumed trend rate(s) starting after one year from the current statement of financial position date.

+ 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=65897934&loc=d3e1928-114920

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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
-Glossary Health Care Cost Trend Rate
-URI http://asc.fasb.org/extlink&oid=6514820

Reference 2: 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=65897934&loc=d3e1928-114920

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- Definition

The ultimate trend rate for health care costs.

+ References

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- Definition

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

+ References

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