Postretirement Health Care and Life Insurance Benefits (Details 4) - Postretirement Health Care and Life Insurance Benefits [Member] $ in Millions	Dec. 31, 2016 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Estimated net actuarial loss that will be amortized from accumulated other comprehensive (income) loss	$ 22.0
Estimated Future Benefit Payments
Postretirement Benefits, 2017	55.0
Postretirement Benefits, 2018	56.2
Postretirement Benefits, 2019	57.0
Postretirement Benefits, 2020	57.5
Postretirement Benefits, 2021	61.3
Postretirement Benefits, Years 2022-2025	290.3
Prior service (cost) credit for the period	$ 9.2

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.

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- References

No definition available.

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- Definition

Amount included in accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan expected to be recognized in net periodic benefit (cost) credit for fiscal year following most recent annual statement of financial position.

+ 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 (s)
-URI http://asc.fasb.org/extlink&oid=82843861&loc=d3e1928-114920

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- Definition

Amount included in accumulated other comprehensive (income) loss for prior service cost (credit) expected to be recognized in net periodic benefit cost (credit) for fiscal year following most recent annual statement of financial position.

+ References

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- Definition

Amount of benefits for defined benefit plan expected to be paid in five fiscal years after fifth fiscal year following latest fiscal year.

+ References