Postretirement Benefits Other Than Pensions - Actuarial Assumptions of OPEB Expense (Details) - Other Postretirement Benefit Plan, Defined Benefit [Member]	12 Months Ended
Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Defined Benefit Plan Disclosure [Line Items]
Discount Rate	3.70%	3.40%	4.00%
Weighted-average Discount Rate	4.21%	0.00%	0.00%
Interest Cost Discount Rate	2.90%	0.00%	0.00%
Rate of Increase in Future Compensation Levels	2.64%	2.68%	2.10%

Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Interest Cost Discount Rate

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- Definition

Defined Benefit Plan, Assumptions Used in Calculating Net Periodic Benefit Cost, Service Cost Discount Rate

+ References

No definition available.

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- Definition

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

+ 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 (k)(1)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

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

+ 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 (k)(2)
-URI http://asc.fasb.org/extlink&oid=65897934&loc=d3e1928-114920

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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